Optical member, laser module including said optical member, and laser device

ABSTRACT

The present disclosure provides an optical member for use in a laser module that includes a surface emitting laser, the optical member being capable of detecting damage (cracking, peeling, and the like), a method for manufacturing the optical member, a laser module including the optical member, and a laser device.

TECHNICAL FIELD

The present invention relates to an optical member for use in a lasermodule including a surface emitting laser light source, a method formanufacturing the same, a laser module including the optical member, anda laser device. The present application claims the rights of priority toJP 2018-213241 filed in Japan on Nov. 13, 2018, and JP 2019-150039 filedin Japan on Aug. 19, 2019, the content of which is incorporated herein.

BACKGROUND ART

The demand for 3D sensing for recognizing the three-dimensional shape ofan object, such as face authentication for avoidance of security risksassociated with the popularization of smartphones, a recognition camerafor 3D mapping, a gesture recognition controller for a gaming device,automatic driving of an automobile, and machine vision in a plant, hasrapidly increased in recent years. Such 3D sensing employs a Time ofFlight (TOF) method, a structured light method, and the like. In thesemethods, laser light is emitted to an object from a laser light sourcesuch as a Vertical Cavity Surface Emitting Laser (VCSEL) to obtaininformation from reflected light.

In such 3D sensing, depending on the application and purpose thereof,laser light is controlled and shaped using an optical member includingan optical element such as a diffuser, a diffractive optical element, alens, a prism, a polarizing plate, or the like. For example, in the TOFmethod, a diffuser is used as an optical element for attaining uniformlaser light, and in the structured light method, laser light iscontrolled and shaped into structured light of a dot pattern or the likeusing a diffractive optical element (for example, Patent Documents 1 to3).

CITATION LIST Patent Document

Patent Document 1: JP 2017-26662 A

Patent Document 2: JP 2018-511034 T

Patent Document 3: JP 2006-500621 T

SUMMARY OF INVENTION Technical Problem

In 3D sensing, near infrared radiation at 850 nm and 940 nm, which hasrelatively high safety, is often used as the laser light. However, highpower light, such as laser light, may be emitted directly to the eyes inthe case of face authentication of a smartphone, which can lead to harm,such as blindness. An optical member including a diffuser, a diffractiveoptical element, or the like diffuses the laser light, and thus alsoserves to reduce such harm. However, in cases where damage such ascracking or peeling occurs in the optical member due to a drop, impact,or the like, the laser light that has not been diffused is directlyemitted to the eyes. Also, if the optical member is degraded or damagedin a 3D sensing system used outdoors and thus in a harsh environmentsuch as sunlight, vibration, or the like, for example, in the case ofautomatic driving of an automobile, accidents may occur due to erroneousactuation, and such defects need to be detected quickly. However, inknown 3D sensing systems, the means for detecting damage to the opticalmember is not known, and it is a current situation that the opticalmember continues to be used without such damage being found.

Therefore, an object of the present invention is to provide an opticalmember for use in a laser module including a surface emitting laser, theoptical member being capable of detecting damage (cracking, peeling, andthe like), and a method for manufacturing the optical member.

Another object of the present invention is to provide a laser moduleincluding the optical member.

Yet another object of the present invention is to provide a laser deviceincluding the laser module.

Note that the laser module typically undergoes a reflow process forbonding an electrode to a wiring board by soldering. In recent years,high melting point lead-free solder has been used as the solder as abonding material, and heating treatment in the reflow process has becomehigher in temperature (for example, a peak temperature of from 240 to260° C.). In such a situation, a problem has occurred in known lasermodules, such as the occurrence of cracking in optical members includingan optical element such as a microlens array, a diffractive opticalelement, or the like, due to heat treatment in the reflow process.Therefore, the optical member used in the laser module is required tohave excellent heat resistance, in particular, a property of being notprone to cracking or peeling even when heat treated in the reflowprocess.

Solution to Problem

As a result of diligent research to solve the problems described above,the present inventors have discovered that damage to an optical membercan be detected by applying a wire containing an electrically conductivesubstance on an optical member used in a laser module, and monitoring aconducting state of the wire. It has also been discovered that the wirecan be easily and efficiently formed by applying an ink containing anelectrically conductive substance to the optical member using a printingprocess. The present invention was completed based on these findings.

Specifically, the present invention provides an optical member for usein a laser module that includes a surface emitting laser light source,the optical member including a wire containing an electricallyconductive substance.

In the optical member, the electrically conductive substance may includea metal.

In the optical member, the electrically conductive substance may includesilver.

The optical member may include at least one type of optical elementselected from the group consisting of a diffractive optical element anda microlens array.

The optical member may be plastic or a laminate of plastic and inorganicglass.

The plastic may be a cured product of a curable epoxy resin composition.

The present invention also provides a laser module including the opticalmember and a surface emitting laser light source.

The laser module further includes a conduction detection mechanism fordetecting a conducting state of the wire containing the electricallyconductive substance, which is included in the optical member.

The present invention also provides a laser device including the lasermodule.

The present invention also provides a method for manufacturing theoptical member, including applying an ink containing an electricallyconductive substance to an optical member by a printing process to formthe wire.

In the method for manufacturing the optical member, the printing processmay include inkjet printing or screen printing.

In the method for manufacturing the optical member, the optical membermay be an optical element array in which two or more optical elementsare arranged two-dimensionally.

The method for manufacturing the optical member may further includesingulating the optical element array into the two or more opticalelements by dicing.

Advantageous Effects of Invention

The optical member of the present invention has the configurationdescribed above, and thus can easily detect damage such as cracking,peeling, and the like of the optical member used in the laser module.Therefore, defects of the laser module caused by damage to the opticalmember and injuries caused by erroneous actuation can be prevented. Forexample, in face authentication of a smartphone, attention can beattracted by sending an error message to the user, or the laser lightitself is not emitted, thereby preventing the user's eyes from beingdirectly irradiated with the laser light and reducing a risk ofblindness and the like. Also, in automatic driving of an automobile,defects in a 3D sensing system mounted with the laser module aredetected, and error messages or the like are sent to the driver, therebymaking it possible to prevent accidents caused by erroneous actuation.In addition, the wire containing an electrically conductive substancecan be easily and efficiently formed in the optical member of thepresent invention by an existing printing process.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1, diagrams (a), (b), and (c) are schematic diagrams illustratingan example of a preferred embodiment of the optical member of thepresent invention. FIG. 1, diagram (a) is a perspective view, FIG. 1,diagram (b) is a top view, and FIG. 1, diagram (c) is a side view.

FIG. 2, diagram (a) and (b) are schematic diagrams illustrating anotherexample of the preferred embodiment of the optical member of the presentinvention.

FIG. 2, diagram (a) is a top view, and FIG. 2, diagram (b) is across-sectional view taken along X-X′.

FIG. 3, diagram (a) and (b) are schematic views illustrating an exampleof a preferred embodiment of the laser module of the present invention.FIG. 3, diagram (a) is a perspective view, and FIG. 3, diagram (b) is across-sectional view taken along Y-Y′ and Z-Z′.

FIG. 4 is a schematic cross-sectional view illustrating another exampleof the preferred embodiment of the laser module of the presentinvention.

DESCRIPTION OF EMBODIMENTS

[Optical Member]

The optical member according to an embodiment of the present inventionis an optical member for use in a laser module that includes a surfaceemitting laser light source, in which the optical member includes a wirecontaining an electrically conductive substance.

Any material that can be used in the optical field can be adopted,without particular limitation, as the material constituting the opticalmember according to an embodiment of the present invention. For example,plastic, optical glass such as BK7 or SF2, quartz glass such assynthetic quartz, or inorganic glass such as calcium fluoride crystalscan be used. Among these, an optical member formed from plastic that iseasily molded and processed is preferred.

Furthermore, from the perspective of providing superior heat resistancethat does not easily cause cracking or peeling even during heattreatment in the reflow process, the optical member is also preferablyan optical member formed from a hybrid material that is a laminate ofplastic and inorganic glass (hereinafter, also referred to as “hybridoptical member”). The hybrid optical member is not particularly limitedas long as it has a laminate structure of plastic and inorganic glass,and examples thereof include a laminate of a plastic layer on one orboth sides of a substrate formed from inorganic glass on which anoptical element is formed; and a laminate in which a plastic layer onwhich an optical element is formed is laminated on one or both side of asubstrate made of flat inorganic glass on which no optical element isformed. The hybrid optical member is preferably a laminate in which aplastic layer on which an optical element is formed on one side of asubstrate made of flat inorganic glass because the optical element iseasily formed.

As the plastic that constitutes the optical member according to anembodiment of the present invention, a plastic that can be used in theoptical field can be adopted without particular limitation. For example,a thermoplastic resin composition and a curable resin composition can beused. However, a curable resin composition having excellent massproductivity and moldability is preferred.

As the thermoplastic resin composition constituting the optical memberaccording to an embodiment of the present invention, a thermoplasticresin composition that can be used in the optical field can be adoptedwithout particular limitation, and examples thereof include(meth)acrylic resins, alicyclic structure-containing resins,styrene-based resins, polyamide resins, polycarbonate resins, polyesterresins, polyether resins, urethane resins, and thiourethane resins.These thermoplastic resins can be molded into the optical memberaccording to an embodiment of the present invention by known moldingmethods such as press molding, extrusion molding, and injection molding,but injection molding is preferable from the perspective of moldabilityand productivity.

As the curable resin composition constituting the optical memberaccording to an embodiment of the present invention, a curable resincomposition that can be used in the optical field can be adopted withoutparticular limitation, and examples thereof include epoxy-based cationiccurable resin compositions, acrylic radical curable resin compositions,and curable silicone resin compositions. Of these, an epoxy-basedcationic curable resin composition (curable epoxy resin composition)that cures in a short time, has a short casting time to a mold, a smallcuring shrinkage rate and excellent dimensional stability, and does notundergo oxygen inhibition during curing is preferred.

As the epoxy resin, a well-known or commonly used compound having one ormore epoxy groups (oxirane ring) in a molecule can be used, and examplesthereof include alicyclic epoxy compounds, aromatic epoxy compounds, andaliphatic epoxy compounds. In an embodiment of the present invention,among them, in terms of being able to form a cured product withexcellent heat resistance and transparency, especially, being able toform an excellent cured product that does not easily cause cracking orpeeling even during heat treatment in the reflow process, apolyfunctional alicyclic epoxy compound having an alicyclic structureand two or more epoxy groups as functional groups in one molecule ispreferred.

Examples of the polyfunctional alicyclic epoxy compounds specificallyinclude:

(i) a compound having an epoxy group constituted of two adjacent carbonatoms and an oxygen atom that constitute an alicyclic ring (i.e., analicyclic epoxy group);

(ii) a compound having an epoxy group directly bonded to an alicyclicring with a single bond; and

(iii) a compound having an alicyclic ring and a glycidyl group.

An example of the above compound (i) having an alicyclic epoxy groupincludes a compound represented by Formula (i) below.

In Formula (i) above, X represents a single bond or a linking group (adivalent group having one or more atoms). Examples of the linking groupinclude a divalent hydrocarbon group, an epoxidized alkenylene group inwhich carbon-carbon double bonds are partially or entirely epoxidized, acarbonyl group, an ether bond, an ester bond, a carbonate group, anamide group, and a linked group in which a plurality of the above islinked. Note that a substituent (for example, such as an alkyl group)may be bonded to a cyclohexene oxide group in Formula (i).

Examples of the divalent hydrocarbon group include a linear or branchedalkylene group having from 1 to 18 carbon atoms and a divalent alicyclichydrocarbon group. Examples of the linear or branched alkylene grouphaving from 1 to 18 carbon atoms include a methylene group, amethylmethylene group, a dimethylmethylene group, an ethylene group, apropylene group, and a trimethylene group. Examples of the divalentalicyclic hydrocarbon group include a cycloalkylene group (including acycloalkylidene group), such as a 1,2-cyclopentylene group, a1,3-cyclopentylene group, a cyclopentylidene group, a 1,2-cyclohexylenegroup, a 1,3-cyclohexylene group, a 1,4-cyclohexylene group, and acyclohexylidene group.

Examples of the alkenylene group in the epoxidized alkenylene group inwhich one, some, or all carbon-carbon double bond(s) is (are) epoxidized(which may be referred to as the “epoxidized alkenylene group”) includea linear or branched alkenylene group having from 2 to 8 carbon atoms,such as a vinylene group, a propenylene group, a 1-butenylene group, a2-butenylene group, a butadienylene group, a pentenylene group, ahexenylene group, a heptenylene group, and an octenylene group. Inparticular, the epoxidized alkenylene group is preferably an epoxidizedalkenylene group in which all of the carbon-carbon double bond(s) is/areepoxidized and more preferably an epoxidized alkenylene group havingfrom 2 to 4 carbon atoms in which all of the carbon-carbon doublebond(s) is/are epoxidized.

The linking group in the above X is, in particular, preferably a linkinggroup containing an oxygen atom, and specifically, examples thereofinclude —CO—, —O—CO—O—, —COO—, —O—, —CONH—, and an epoxidized alkenylenegroup; a group in which a plurality of these groups are linked; and agroup in which one or two or more of these groups and one or more of thedivalent hydrocarbon groups are linked.

Representative examples of the compound represented by Formula (i) aboveinclude (3,4,3′,4′-diepoxy)bicyclohexyl,bis(3,4-epoxycyclohexylmethyl)ether,1,2-epoxy-1,2-bis(3,4-epoxycyclohexane-1-yl)ethane,2,2-bis(3,4-epoxycyclohexane-1-yl)propane,1,2-bis(3,4-epoxycyclohexane-1-yl)ethane, and compounds represented byFormulas (i-1) to (i-10) below. L in Formula (i-5) below is an alkylenegroup having from 1 to 8 carbons, and, among them, preferably a linearor branched alkylene group having from 1 to 3 carbons, such as amethylene group, an ethylene group, a propylene group, or anisopropylene group. In Formulas (i-5), (i-7), (i-9), and (i-10) below,n¹ to n⁸ each represent an integer of 1 to 30.

The above compound (i) having an alicyclic epoxy group also includes anepoxy-modified siloxane.

Examples of the epoxy-modified siloxane include a chain or cyclicpolyorganosiloxane having a constituent unit represented by Formula (i′)below.

In Formula (i′) above, R¹ represents a substituent containing an epoxygroup represented by Formula (1a) or (1b) below, and R² represents analkyl group or an alkoxy group.

In the formulas, R^(1a) and R^(1b) are the same or different andrepresent a linear or branched alkylene group, and examples thereofinclude a linear or branched alkylene group having from 1 to 10 carbons,such as a methylene group, a methyl methylene group, a dimethylmethylene group, an ethylene group, a propylene group, a trimethylenegroup, a tetramethylene group, a pentamethylene group, a hexamethylenegroup, and a decamethylene group.

The epoxy equivalent (in accordance with JIS K7236) of theepoxy-modified siloxane is, for example, from 100 to 400 and preferablyfrom 150 to 300.

As the epoxy-modified siloxane, for example, commercially availableproducts can be used, for example, such as an epoxy-modified cyclicpolyorganosiloxane represented by Formula (i′-1) below (trade name“X-40-2670”, available from Shin-Etsu Chemical Co., Ltd.).

Examples of the above compound (ii) having an epoxy group directlybonded to an alicyclic ring with a single bond include a compoundrepresented by Formula (ii) below.

In Formula (ii), R′ is a group resulting from elimination of p hydroxylgroups (—OH) from a structural formula of a p-hydric alcohol (p-valentorganic group), and p and n⁹ each represent a natural number. Examplesof the p-hydric alcohol [R′—(OH)_(p)] include polyhydric alcohols(alcohols having from 1 to 15 carbon atoms), such as2,2-bis(hydroxymethyl)-1-butanol. Here, p is preferably from 1 to 6, andn⁹ is preferably from 1 to 30. When p is 2 or greater, n⁹ in each groupin square brackets (the outer brackets) may be the same or different.Examples of the compound represented by Formula (ii) above specificallyinclude 1,2-epoxy-4-(2-oxiranyl)cyclohexane adduct of2,2-bis(hydroxymethyl)-1-butanol [for example, such as the trade name“EHPE3150” (available from Daicel Corporation)].

Examples of the above compound (iii) having an alicyclic ring and aglycidyl group include hydrogenated aromatic glycidyl ether-based epoxycompounds, such as a hydrogenated bisphenol A epoxy compound, ahydrogenated bisphenol F epoxy compound, a hydrogenated bisphenol epoxycompound, a hydrogenated phenol novolac epoxy compound, a hydrogenatedcresol novolac epoxy compound, a hydrogenated cresol novolac epoxycompound of bisphenol A, a hydrogenated naphthalene epoxy compound, anda hydrogenated product of a trisphenol methane epoxy compound.

The polyfunctional alicyclic epoxy compound is preferably the compound(i) having an alicyclic epoxy group and particularly preferably acompound represented by Formula (i) above (in particular,(3,4,3′,4′-diepoxy)bicyclohexyl), in terms of providing a cured producthaving high surface hardness and excellent transparency.

The curable resin composition in an embodiment of the present inventionmay contain an additional curable compound in addition to the epoxyresin as the curable compound and can contain, for example, one type, ortwo or more types of cationic curable compounds, such as an oxetanecompound and a vinyl ether compound.

A proportion of the epoxy resin in a total amount (100 wt. %) of thecurable compound contained in the curable resin composition is, forexample, 50 wt. % or greater, preferably 60 wt. % or greater,particularly preferably 70 wt. % or greater, most preferably 80 wt. % orgreater, and the upper limit is, for example, 100 wt. % and preferably90 wt. %.

In addition, a proportion of the compound (i) having an alicyclic epoxygroup in the total amount (100 wt. %) of the curable compound containedin the curable resin composition is, for example, 20 wt. % or greater,preferably 30 wt. % or greater, particularly preferably 40 wt. % orgreater, and the upper limit is, for example, 70 wt. % and preferably 60wt. %.

A proportion of the compound represented by Formula (i) in the totalamount (100 wt. %) of the curable compound contained in the curableresin composition is, for example, 10 wt. % or greater, preferably 15wt. % or greater, particularly preferably 20 wt. % or greater, and theupper limit is, for example, 50 wt. % and preferably 40 wt. %.

The curable resin composition preferably contains a polymerizationinitiator along with the curable compound, and particularly preferablycontains one or more photopolymerization or thermal polymerizationinitiators (photocationic or thermal cationic polymerizationinitiators).

The photocationic polymerization initiator is a compound that initiatescuring reaction of the curable compound (in particular, the cationiccurable compound) contained in the curable resin composition bygenerating an acid with light irradiation and is formed of a cationicmoiety that absorbs light and an anionic moiety that serves as a sourcefor generating the acid.

Examples of the photocationic polymerization initiator include diazoniumsalt-based compounds, iodonium salt-based compounds, sulfoniumsalt-based compounds, phosphonium salt-based compounds, seleniumsalt-based compounds, oxonium salt-based compounds, ammonium salt-basedcompounds, and bromine salt-based compounds.

In the present invention, among these, use of a sulfonium salt-basedcompound is preferred because a cured product having excellentcurability can be formed. Examples of the cationic moiety of thesulfonium salt-based compound include arylsulfonium ions (in particular,triarylsulfonium ions), such as a (4-hydroxyphenyl)methylbenzylsulfoniumion, a triphenyl sulfonium ion, adiphenyl[4-(phenylthio)phenyl]sulfonium ion, a4-(4-biphenylthio)phenyl-4-biphenylylphenylsulfonium ion, and atri-p-tolylsulfonium ion.

Examples of the anion moiety of the photocationic polymerizationinitiator include [(Y)_(s)B(Phf)_(4-s)]⁻ (in the formula, Y represents aphenyl group or a biphenylyl group, Phf represents a substituted phenylgroup in which at least one of hydrogen atoms is replaced with at leastone selected from a perfluoroalkyl group, a perfluoroalkoxy group, or ahalogen atom, and s is an integer of 0 to 3.), BF₄ ⁻,[(Rf)_(t)PF_(6-t)]⁻ (in the formula, Rf represents an alkyl group inwhich 80% or more of hydrogen atoms are replaced with fluorine atoms,and t represents an integer of 0 to 5; AsF₆ ⁻; SbF₆ ⁻; and SbF₅OH⁻.

Examples of the photocationic polymerization initiator that can be usedinclude (4-hydroxyphenyl)methylbenzylsulfoniumtetrakis(pentafluorophenyl)borate;4-(4-biphenylylthio)phenyl-4-biphenylylphenylsulfoniumtetrakis(pentafluorophenyl)borate; 4-(phenylthio)phenyldiphenylsulfoniumphenyltris(pentafluorophenyl)borate;[4-(4-biphenylylthio)phenyl]-4-biphenylylphenylsulfoniumphenyltris(pentafluorophenyl)borate;diphenyl[4-(phenylthio)phenyl]sulfoniumtris(pentafluoroethyl)trifluorophosphate;diphenyl[4-(phenylthio)phenyl]sulfoniumtetrakis(pentafluorophenyl)borate;diphenyl[4-(phenylthio)phenyl]sulfonium hexafluorophosphate;4-(4-biphenylylthio)phenyl-4-biphenylylphenylsulfoniumtris(pentafluoroethyl)trifluorophosphate;bis[4-(diphenylsulfonio)phenyl]sulfidephenyltris(pentafluorophenyl)borate;[4-(2-thioxanthonylthio)phenyl]phenyl-2-thioxanthonylsulfoniumphenyltris(pentafluorophenyl)borate;4-(phenylthio)phenyldiphenylsulfonium hexafluoroantimonate; andcommercially available products under trade names, such as “CyracureUVI-6970”, “Cyracure UVI-6974”, “Cyracure UVI-6990”, and “CyracureUVI-950” (these are available from Union Carbide Corporation, USA),“Irgacure 250”, “Irgacure 261”, “Irgacure 264”, and “CG-24-61” (theseare available from BASF), “Optomer SP-150”, “Optomer SP-151”, “OptomerSP-170”, and “Optomer SP-171” (these are available from AdekaCorporation), “DAICAT II” (available from Daicel Corporation), “UVAC1590” and “UVAC 1591” (these are available from Daicel-Cytec Co., Ltd.),“CI-2064”, “CI-2639”, “CI-2624”, “CI-2481”, “CI-2734”, “CI-2855”,“CI-2823”, “CI-2758”, and “CIT-1682” (these are available from NipponSoda Co., Ltd.), “PI-2074” (tetrakis(pentafluorophenyl)boratetricumyliodonium salt, available from Rhodia), “FFC 509” (available from3M), “BBI-102”, “BBI-101”, “BBI-103”, “MPI-103”, “TPS-103”, “MDS-103”,“DTS-103”, “NAT-103”, and “NDS-103” (these are available from MidoriKagaku Co., Ltd.), “CD-1010”, “CD-1011”, and “CD-1012” (these areavailable from Sartomer, USA), and “CPI-100P” and “CPI-101A” (these areavailable from San-Apro Ltd.).

The thermal cationic polymerization initiator is a compound thatinitiates a curing reaction of the cationic curable compound containedin the curable resin composition by generating an acid with heatingtreatment and is formed of a cationic moiety that absorbs heat and ananionic moiety that serves as a source for generating the acid. A singlethermal cationic polymerization initiator can be used alone, or two ormore thermal cationic polymerization initiators can be used incombination.

Examples of the thermal cationic polymerization initiator includeiodonium salt compounds, and sulfonium salt compounds.

Examples of the cationic moiety of the thermal cationic polymerizationinitiator include 4-hydroxyphenyl-methyl-benzylsulfonium ions,4-hydroxyphenyl-methyl-(2-methylbenzyl)sulfonium ions,4-hydroxyphenyl-methyl-1-naphthylmethylsulfonium ions, andp-methoxycarbonyloxyphenyl-benzyl-methylsulfonium ions.

Examples of the anionic moiety of the thermal cationic polymerizationinitiator include the same examples as those of the anionic moiety ofthe photocationic polymerization initiator indicated above.

Examples of the thermal cationic polymerization initiator include4-hydroxyphenyl-methyl-benzylsulfonium phenyl tris(pentafluorophenyl)borate, 4-hydroxyphenyl-methyl-(2-methylbenzyl) sulfonium phenyltris(pentafluorophenyl) borate,4-hydroxyphenyl-methyl-1-naphthylmethylsulfonium phenyltris(pentafluorophenyl) borate, andp-methoxycarbonyloxyphenyl-benzyl-methylsulfonium phenyltris(pentafluorophenyl) borate.

The content of the polymerization initiator is, for example, in a rangeof 0.1 to 5.0 parts by weight relative to 100 parts by weight of thecurable compound (in particular, the cationic curable compound)contained in the curable resin composition. When the content of thephotopolymerization initiator is less than the above range, curingfailures may occur. On the other hand, when the content of thephotopolymerization initiator exceeds the above range, coloration of thecured product tends to occur.

The curable resin composition in the present invention can be producedby mixing the curable compound, the polymerization initiator, and, asnecessary, an additional component (for example, such as a solvent, anantioxidant, a surface conditioner, a photosensitizer, an anti-foamingagent, a leveling agent, a joining agent, a surfactant, a flameretardant, an ultraviolet absorber, and a colorant). The additionalcomponent is blended in an amount of, for example, 20 wt. % or less,preferably 10 wt. % or less, particularly preferably 5 wt. % or less ofthe total amount of the curable resin composition.

The viscosity of the curable resin composition of the present inventionat 25° C. is not particularly limited, but is preferably 5000 mPa·s orless, more preferably 2500 mPa·s or less. Adjusting the viscosity of thecurable resin composition according to an embodiment of the presentinvention to the above-described range may improve fluidity, andsuppress air bubble residues. Thus, it is possible to fill the curableresin composition into a mold while suppressing the increase ininjection pressure. That is, coatability and fillability can beimproved, and workability can be improved throughout the moldingoperation of the curable resin composition according to an embodiment ofthe present invention. The viscosity in the present specification is avalue measured using a rheometer (“PHYSICA UDS200” available from PaarPhysica) under the conditions of a temperature of 25° C. and arotational speed of 20/sec.

Commercially available products such as the trade names “CELVENUSOUH106” and “CELVENUS OTM107” (there are available from DaicelCorporation) can also be used as the curable resin composition in thepresent invention.

The optical member according to an embodiment of the present inventioncan obtain an optical member formed from a cured product of the curableresin composition by molding the curable resin composition using a moldand then curing.

Examples of the method for molding the curable resin composition using amold include methods (1) and (2) below.

(1) A method of applying the curable resin composition to a mold,pressing a substrate from above, curing the curable resin composition,and then detaching the mold; and

(2) A method of applying the curable resin composition to at least oneof an upper mold or a lower mold, combining the upper mold and the lowermold, curing the curable resin composition, and then detaching the uppermold and the lower mold.

For example, when a photocurable resin composition is used as thecurable resin composition, a substrate having a light transmittance of90% or greater at a wavelength of 400 nm is preferably used as thesubstrate described above, and a substrate made of inorganic glass suchas quartz glass or optical glass can be suitably used. In the method (1)above, when a substrate made of inorganic glass is used, a hybridoptical member that is a laminate of a cured product of a curable resincomposition and inorganic glass can be obtained. Further, the lighttransmittance at the wavelength can be determined using a substrate(thickness: 1 mm) as a test piece and using a spectrophotometer tomeasure the light transmittance at the wavelength irradiated to the testpiece.

The method of applying the curable resin composition is not particularlylimited, and examples thereof include methods using a dispenser, asyringe, or the like. Furthermore, the curable resin composition ispreferably applied to a center portion of the mold.

For example, when a photocurable resin composition is used as thecurable resin composition, the curable resin composition can be cured byultraviolet irradiation. Examples of the light source used during theultraviolet light irradiation include a high-pressure mercury-vaporlamp, an ultrahigh-pressure mercury-vapor lamp, a carbon-arc lamp, axenon lamp, and a metal halide lamp. The irradiation time is dependentof the type of the light source, the distance between the light sourceand the coated surface, and other conditions, but is several tens ofseconds at the longest. The illuminance is approximately from 5 to 200mW. After the ultraviolet light irradiation, the curable composition maybe heated (post-curing) as necessary to facilitate curing.

For example, when a thermosetting resin composition is used as thecurable resin composition, the curable resin composition can be cured byheating treatment. The heating temperature is, for example,approximately from 60 to 150° C. The heating time is, for example,approximately from 0.2 to 20 hours.

The shape of the optical member according to an embodiment of thepresent invention is not particularly limited as long as it can be usedin the optical field, and can be selected, for example, from a plateshape, a sheet shape, a film shape, a lens shape, a prism shape, acolumnar shape, a conical shape, and the like depending on the purposeand application. A substrate shape such as a plate shape, a sheet shape,a film shape, or the like is preferred from the perspective of easilycontrolling the laser light, when the optical member includes an opticalelement described below. When the optical member according to anembodiment of the present invention has a substrate shape, the thicknessthereof can also be appropriately set depending on the application andpurpose, and can be appropriately selected from a range of from 100 to2000 μm, and preferably from 100 to 1000 μm.

The optical member according to an embodiment of the present inventionpreferably has high transparency. The total light transmittance of theoptical member according to an embodiment of the present invention isnot particularly limited but is preferably 70% or greater and morepreferably 80% or greater. In addition, the upper limit of the totallight transmittance is not particularly limited but is, for example,99%. The total light transmittance of the optical member according to anembodiment of the present invention can be easily controlled to theabove range, for example, by using the cured product of the curableresin composition described above as the material. Here, the total lighttransmittance can be measured according to JIS K7361-1.

The haze of the optical member according to an embodiment of the presentinvention is not particularly limited but is preferably 10% or less andmore preferably 5% or less. In addition, the lower limit of the haze isnot particularly limited but is, for example, 0.1%. The haze of theoptical member according to an embodiment of the present invention canbe easily controlled to the above range, for example, by using the curedproduct of the curable resin composition described above as thematerial. Here, the haze can be measured according to JIS K7136.

The optical member according to an embodiment of the present inventionpreferably includes an optical element. As the optical element includedin the optical member according to an embodiment of the presentinvention, an optical element that can be used in the optical field canbe adopted without particular limitation, and examples thereof includediffractive optical elements, microlens arrays, prisms, and polarizingplates. A diffractive optical element and a microlens array, which aresuitable for controlling the laser light, are preferred.

The diffractive optical element (DOE) is an optical element that uses adiffraction phenomenon of light such as grating hologram to change thetraveling direction of the light, which diffracts light by a periodicstructure (diffraction groove) formed in the optical member and formsthe light into any structural light. The structural light of the laserlight that is controlled by the diffractive optical element included inthe optical member according to an embodiment of the present inventionis not particularly limited, but examples thereof include a dot pattern,and uniform surface irradiated light. The structural light can beappropriately selected depending on the application and purpose.

The microlens array has a structure in which a plurality of microlenseshaving a size of approximately tens of μm are arranged, and functions asa “diffuser” that diffuses and uniformizes the laser light emitted fromthe surface emitting laser light source. The respective microlensesconstituting the microlens array may have the same shape, or themicrolens array may have a random structure in which microlensesdifferent in shape are arranged. Whether the microlenses have the sameshape or different shapes may be appropriately selected depending on theapplication and purpose.

The optical element included in the optical member according to anembodiment of the present invention can be formed by a known method. Forexample, a mold having a molding surface having an inverted shape to theshape of a desired optical element is used as the mold for molding thecurable resin composition described above, and thus the optical elementcan be formed in a region corresponding to the inverted shape of theoptical member. Furthermore, a method of forming a desired opticalpattern on the optical member by electron beam lithography or the likemay also be adopted.

In addition, a member including an optical element may be separatelylaminated onto an optical member that does not include an opticalelement. A material similar to the material constituting the opticalmember according to an embodiment of the present invention can be usedas the material constituting the member including an optical element.The material that constitutes the member including an optical elementmay be the same material as or a different material from the materialconstituting the optical member according to an embodiment of thepresent invention. The member including an optical element can beavailable from a method similar to the method for manufacturing theoptical member including the optical element according to an embodimentof the present invention.

The optical element included in the optical member according to anembodiment of the present invention may be formed entirely on thesurface of the optical member or may be formed partially thereon.Specifically, in a case where the optical member has a substrate shape,an optical element may be formed entirely on at least one side of theoptical member, or an optical element may be formed partially thereon.Additionally, an optical element may be formed on only one side of thesubstrate-shaped optical member, or an optical element may be formed onboth sides thereof.

An aspect is preferred in which a substrate-shaped optical memberincluding an optical element preferably includes a region in which anoptical element is formed (hereinafter, also referred to as “opticalelement region”) and a region in which no optical element is formed(hereinafter, also referred to as “non-optical element region”).Especially, an aspect is preferred in which the optical element regionis formed in a center portion of the substrate of the optical member,and the non-optical element region is provided on the periphery of theoptical element region (outer periphery of the substrate of the opticalmember). Note that, even in a case where an optical element is formed ononly one side of the substrate-shaped optical member, regionscorresponding to the optical element region and the non-optical elementregion are also interpreted as the optical element region and thenon-optical element region, respectively, on the other side on which nooptical element is formed.

[Wire Containing Electrically Conductive Substance]

The optical member according to an embodiment of the present inventionincludes a wire containing an electrically conductive substance.

The electrically conductive substance is not particularly limited aslong as it has electrical conductivity, and for example, a metal, ametal oxide, an electrically conductive polymer, an electricallyconductive carbon-based substance, or the like can be used.

Examples of the metal include gold, silver, copper, chromium, nickel,palladium, aluminum, iron, platinum, molybdenum, tungsten, zinc, lead,cobalt, titanium, zirconium, indium, rhodium, ruthenium, and alloysthereof. Examples of the metal oxide include chromium oxide, nickeloxide, copper oxide, titanium oxide, zirconium oxide, indium oxide,aluminum oxide, zinc oxide, tin oxide, or composite oxides thereof suchas composite oxides of indium oxide and tin oxide (ITO) and complexoxides of tin oxide and phosphorus oxide (PTO). Examples of theelectrically conductive polymer include polyacetylene, polyaniline,polypyrrole, and polythiophene. Examples of the electrically conductivecarbon-based substance include carbon black, SAF, ISAF, HAF, FEF, GPF,SRF, FT, MT, pyrolytic carbon, natural graphite, and artificialgraphite. These electrically conductive substances can be used alone, ortwo or more types thereof can be used in combination.

The electrically conductive substance is preferably a metal or metaloxide having excellent electrical conductivity and easy to form a wire,and more preferably a metal. Gold, silver, copper, indium, or the likeis preferred, and silver is particularly preferred because it ismutually fused at a temperature of approximately 100° C. and can form awire with excellent electrical conductivity even on a plastic opticalmember.

In addition to the electrically conductive substance, the wirecontaining the electrically conductive substance may contain an additivesuch as a doping agent, a reducing agent, an antioxidant, a couplingagent (such as a silane coupling agent), or the like, from theperspective of improving electrical conductivity, steady contact withthe optical member, and the like.

As a method for forming the wire containing the electrically conductivesubstance on the optical member, known methods such as a printingprocess, a sputtering method, a vacuum deposition method, a chemicalvapor deposition (CVD) method, a metal organic chemical vapor deposition(MOCVD) method, and a laser ablation method (Pulsed Laser AblationDeposition (PLAD)) can be used without limitation. From the perspectiveof easily forming a wire of a desired width at a target position of theoptical member, a printing process and a sputtering method arepreferred, and a printing process is particularly preferred.

As the printing process, a known printing process can be used withoutparticular limitation, and examples thereof include inkjet printing,gravure printing, flexographic printing, screen printing, and offsetprinting. From the perspective of easily forming a wire of a desiredwidth at a target position of the optical member, inkjet printing,gravure printing, flexographic printing, or screen printing ispreferred, and inkjet printing or screen printing is particularlypreferred.

The inkjet printing according to an embodiment of the present inventionis a method that includes applying an ink containing an electricallyconductive substance from a nozzle to an optical member to form a wire.

The ink containing the electrically conductive substance used in theinkjet printing in the present invention is not particularly limited aslong as it can be used for inkjet printing, but from the perspective ofeasily forming a wire of a desired width at a target position of theoptical member, an ink containing “surface-modified metal nanoparticleshaving a configuration in which surfaces of the metal nanoparticles arecoated with an organic protective agent” (hereinafter, also referred tosimply as “surface-modified metal nanoparticles”) is preferred.

The surface-modified metal nanoparticles have a configuration in whichsurfaces of the metal nanoparticles are coated with an organicprotective agent. As such, the surface-modified metal nanoparticles haveexcellent dispersibility because the spacing between the metalnanoparticles is ensured and thus agglomeration is suppressed.

The surface-modified metal nanoparticles include a metal nanoparticleportion and a surface modification portion that coats the metalnanoparticle portion (i.e., the portion that coats the metalnanoparticles and is formed of an organic protective agent), and theproportion of the surface modification portion is, for example,approximately from 1 to 20 wt. % (preferably from 1 to 10 wt. %) of theweight of the metal nanoparticle portion. Each weight of the metalnanoparticle portion and the surface modification portion in thesurface-modified metal nanoparticles can be determined, for example,from the weight loss rate in a certain temperature range by subjectingthe surface-modified metal nanoparticles to thermogravimetry.

The average primary particle diameter of the metal nanoparticle portionin the surface-modified metal nanoparticles is, for example, from 0.5 to100 nm, preferably from 0.5 to 80 nm, more preferably from 1 to 70 nm,and even more preferably from 1 to 60 nm.

The metal constituting the metal nanoparticle portion of thesurface-modified metal nanoparticles can be a metal having theabove-described electrical conductivity, and examples thereof includegold, silver, copper, nickel, aluminum, rhodium, cobalt, and ruthenium.Silver nanoparticles are preferred as the metal nanoparticles accordingto an embodiment of the present invention in that the silvernanoparticles are fused to each other at a temperature of approximately100° C., and can form a wire having excellent electrical conductivity onthe optical member. Therefore, the surface-modified metal nanoparticlesare preferably surface-modified silver nanoparticles, and a silver inkis preferred as the ink for inkjet printing.

The organic protective agent that constitutes the surface modificationportion of the surface-modified metal nanoparticles is preferably acompound having at least one type of functional group selected from thegroup consisting of a carboxyl group, a hydroxyl group, an amino group,a sulfo group, and a thiol group, particularly preferably a compoundhaving from 4 to 18 carbon atoms and having at least one type offunctional group selected from the group consisting of an amino group, asulfo group, and a thiol group, most preferably a compound having anamino group, and especially preferably a compound having from 4 to 18carbon atoms and having an amino group (i.e., an amine having from 4 to18 carbon atoms).

The surface-modified metal nanoparticles can be manufactured, forexample, through: mixing a metal compound and an organic protectiveagent to form a complex containing the metal compound and the organicprotective agent (formation of the complex); thermally decomposing thecomplex (thermal decomposition); and, as necessary, washing the reactionproduct (washing).

Formation of Complex

The formation of the complex is to mix a metal compound and an organicprotective agent to form a complex containing the metal compound and theorganic protective agent. It is preferable to use a silver compound asthe metal compound, and because the nano-sized silver particles arefused to each other at a temperature of approximately 100° C., and thusa wire having excellent electrical conductivity can be formed on theoptical member. Particularly, a silver compound that is readilydecomposed upon heating and produces metallic silver is preferably used.Examples of such a silver compound include silver carboxylates, such assilver formate, silver acetate, silver oxalate, silver malonate, silverbenzoate, and silver phthalate; silver halides, such as silver fluoride,silver chloride, silver bromide, and silver iodide; and silver sulfate,silver nitrate, and silver carbonate. Among them, silver oxalate ispreferred in that it has a high silver content, can be thermallydecomposed without using a reducing agent, and thus an impurity derivedfrom the reducing agent is less likely to be mixed into the ink.

As the organic protective agent, a compound having at least one type offunctional group selected from the group consisting of a carboxyl group,a hydroxyl group, an amino group, a sulfo group, and a thiol group, inthat the coordination of non-covalent electron pairs in the heteroatomto the metal nanoparticles can exert an effect of strongly suppressingagglomeration between the metal nanoparticles. A compound having from 4to 18 carbon atoms and having at least one type of functional groupselected from the group consisting of a carboxyl group, a hydroxylgroup, an amino group, a sulfo group, and a thiol group is particularlypreferred.

The organic protective agent is preferably a compound having an aminogroup, and most preferably a compound having from 4 to 18 carbon atomsand having an amino group, that is, an amine having from 4 to 18 carbonatoms.

The amine is a compound in which at least one hydrogen atom of ammoniais substituted with a hydrocarbon group, and includes a primary amine, asecondary amine, and a tertiary amine. In addition, the amine may be amonoamine or a polyamine, such as a diamine. One of these solvents canbe used alone or two or more in combination.

The amine preferably contains at least one selected from a monoamine (1)having 6 or more carbon atoms in total and represented by Formula (a-1)below, where R¹, R², and R³ are identical or different and are hydrogenatoms or monovalent hydrocarbon groups (with the provisio that the casein which R¹, R², and R³ are all hydrogen atoms is omitted); monoamine(2) having 5 or less carbon atoms in total and represented by Formula(a-1) below, where R¹, R², and R³ are identical or different and arehydrogen atoms or monovalent hydrocarbon groups (with the provisio thatthe case in which R¹, R², and R³ are all hydrogen atoms is omitted); anda diamine (3) having 8 or less carbon atoms in total and represented byFormula (a-2), where R⁴ to R⁷ are identical or different and arehydrogen atoms or monovalent hydrocarbon groups, and R⁸ is a divalenthydrocarbon group; and in particular, preferably contains the monoamine(1) in combination with the monoamine (2) and/or the diamine (3).

The hydrocarbon group includes an aliphatic hydrocarbon group, analicyclic hydrocarbon group, and an aromatic hydrocarbon group, andamong them, an aliphatic hydrocarbon group or an alicyclic hydrocarbongroup is preferred, and in particular, an aliphatic hydrocarbon group ispreferred. Thus, the monoamine (1), the monoamine (2), and the diamine(3) are preferably an aliphatic monoamine (1), an aliphatic monoamine(2), and an aliphatic diamine (3).

In addition, the monovalent aliphatic hydrocarbon group includes analkyl group and an alkenyl group. The monovalent alicyclic hydrocarbongroup includes a cycloalkyl group and a cycloalkenyl group. Furthermore,the divalent aliphatic hydrocarbon group includes an alkylene group andan alkenylene group, and the divalent alicyclic hydrocarbon groupincludes a cycloalkylene group and a cycloalkenylene group.

Examples of the monovalent hydrocarbon group in R¹, R², and R³ mayinclude alkyl groups having approximately from 1 to 18 carbon atoms,such as a methyl group, an ethyl group, a propyl group, an isopropylgroup, a butyl group, an isobutyl group, an sec-butyl group, atert-butyl group, a pentyl group, a hexyl group, a decyl group, adodecyl group, a tetradecyl group, an octadecyl group; alkenyl groupshaving approximately from 2 to 18 carbon atoms, such as a vinyl group,an allyl group, a methallyl group, a 1-propenyl group, an isopropenylgroup, a 1-butenyl group, a 2-butenyl group, a 3-butenyl group, a1-pentenyl group, a 2-pentenyl group, a 3-pentenyl group, a 4-pentenylgroup, and a 5-hexenyl group; cycloalkyl groups having approximatelyfrom 3 to 18 carbon atoms, such as a cyclopropyl group, a cyclobutylgroup, a cyclopentyl group, a cyclohexyl group, and a cyclooctyl group;and cycloalkenyl groups having approximately from 3 to 18 carbon atoms,such as a cyclopentenyl group and a cyclohexenyl group.

Examples of the monovalent hydrocarbon groups in R⁴ to R⁷ may include,among those exemplified above, alkyl groups having approximately from 1to 7 carbon atoms, alkenyl groups having approximately from 2 to 7carbon atoms, cycloalkyl groups having approximately from 3 to 7 carbonatoms, and cycloalkenyl groups having approximately from 3 to 7 carbonatoms.

Examples of the divalent hydrocarbon group in R⁸ may include alkylenegroups having from 1 to 8 carbon atoms, such as a methylene group, amethylmethylene group, a dimethylmethylene group, an ethylene group, apropylene group, a trimethylene group, a tetramethylene group, apentamethylene group, and a heptamethylene group; and alkenylene groupshaving from 2 to 8 carbon atoms, such as a vinylene group, a propenylenegroup, a 1-butenylene group, a 2-butenylene group, a butadienylenegroup, a pentenylene group, a hexenylene group, a heptenylene group, andan octenylene group.

The hydrocarbon groups in the above R¹ to R⁸ may have a substituent ofvarious types [e.g., such as a halogen atom, an oxo group, a hydroxylgroup, a substituted oxy group (e.g., such as a C₁₋₄ alkoxy group, aC₆₋₁₀ aryloxy group, a C₇₋₁₆ aralkyloxy group, or a C₁₋₄ acyloxy group),a carboxyl group, a substituted oxycarbonyl group (e.g., such as a C₁₋₄alkoxycarbonyl group, a C₆₋₁₀ aryloxycarbonyl group, or a C₇₋₁₆aralkyloxycarbonyl group), a cyano group, a nitro group, a sulfo group,or a heterocyclic group]. In addition, the hydroxyl group and thecarboxyl group may be protected with a protecting group commonly used inthe field of organic synthesis.

The monoamine (1) is a compound that is adsorbed on the surfaces of themetal nanoparticles and prevents agglomeration of the metalnanoparticles and enlargement of the agglomeration, that is, a compoundhaving a function of imparting high dispersibility to the metalnanoparticles. Examples of the monoamine (1) include primary monoamineshaving a linear alkyl group, such as n-hexylamine, n-heptylamine,n-octylamine, n-nonylamine, n-decylamine, n-undecylamine, andn-dodecylamine; primary amines having a branched alkyl group, such asisohexylamine, 2-ethylhexylamine, and tert-octylamine; a primary aminehaving a cycloalkyl group, such as cyclohexylamine; a primary aminehaving an alkenyl group, such as oleylamine; secondary amines having alinear alkyl group, such as N,N-dipropylamine, N,N-dibutylamine,N,N-dipentylamine, N,N-dihexylamine, N,N-dipeptylamine,N,N-dioctylamine, N,N-dinonylamine, N,N-didecylamine,N,N-diundecylamine, N,N-didodecylamine, and N-propyl-N-butylamine;secondary amines having a branched alkyl group, such asN,N-diisohexylamine and N,N-di(2-ethylhexyl)amine; tertiary amineshaving a linear alkyl group, such as tributylamine and trihexylamine;and tertiary amines having a branched alkyl group, such astriisohexylamine and tri(2-ethylhexyl)amine.

Among the above monoamines (1), an amine (in particular, a primaryamine) having a linear alkyl group having from 6 to 18 carbon atoms intotal (more preferably up to 16 and particularly preferably up to 12carbon atoms in total) is preferred in that such an amine can providespace between the metal nanoparticles when the amino groups is adsorbedon the metal nanoparticle surfaces, thus providing the effect ofpreventing agglomeration of the metal nanoparticles, and such an aminecan be easily removed during sintering. In particular, n-hexylamine,n-heptylamine, n-octylamine, n-nonylamine, n-decylamine, n-undecylamine,n-dodedeyclamine, and the like are preferred.

The monoamine (2) has a shorter hydrocarbon chain than that of themonoamine (1), and thus the function of the monoamine (2) itself toimpart high dispersibility to the metal nanoparticles is low. However,the monoamine (2) has a high coordination ability to a metal atom due toits higher polarity than that of the monoamine (1), and thus has aneffect of promoting complex formation. In addition, the monoamine (2)has a short hydrocarbon chain and thus can be removed from the metalnanoparticle surfaces in a short time (e.g., not longer than 30 minutesand preferably not longer than 20 minutes) even in low-temperaturesintering, thus providing a sintered body with excellent electricalconductivity.

Examples of the monoamine (2) include a primary amine having a linear orbranched alkyl group and having from 2 to 5 carbon atoms in total(preferably from 4 to 5 carbon atoms in total), such as n-butylamine,isobutylamine, sec-butylamine, tert-butylamine, pentylamine,isopentylamine, and tert-pentylamine; and a secondary amine having alinear or branched alkyl group and having from 2 to 5 carbon atoms intotal (preferably from 4 to 5 carbon atoms in total), such asN,N-diethylamine. In an embodiment of the present invention, amongthese, a primary amine having a linear alkyl group and having from 2 to5 carbon atoms in total (preferably from 4 to 5 carbon atoms in total)is preferred.

The diamine (3) has 8 or less carbon atoms in total and has a highcoordination ability to a metal atom due to its higher polarity thanthat of the monoamine (1), and thus has an effect of promoting complexformation. In addition, the diamine (3) has an effect of promotingthermal decomposition of the complex at lower temperature and in a shorttime in the thermal decomposition of the complex, and the use of thediamine (3) can perform the production of the surface-modified metalnanoparticles more efficiently. Furthermore, the surface-modified metalnanoparticles having a configuration of being coated with the protectiveagent containing the diamine (3) exhibit excellent dispersion stabilityin a highly polar dispersion medium. Moreover, the diamine (3) has ashort hydrocarbon chain and thus can be removed from the metalnanoparticle surfaces in a short time (e.g., not longer than 30 minutesand preferably not longer than 20 minutes) even by low-temperaturesintering, thus providing a sintered body with excellent electricalconductivity.

Examples of the diamine (3) may include diamines in which R⁴ to R⁷ inFormula (a-2) are hydrogen atoms, and R⁸ is a linear or branchedalkylene group, such as 2,2-dimethyl-1,3-propanediamine,1,4-butanediamine, 1,5-pentanediamine, 1,6-hexanediamine,1,7-heptanediamine, 1,8-octanediamine, and 1,5-diamino-2-methylpentane;diamines in which R⁴ and R⁶ in Formula (a-2) are identical or differentand linear or branched alkyl groups, R⁵ and R⁷ are hydrogen atoms, andR⁸ is a linear or branched alkylene group, such asN,N′-dimethylethylenediamine, N,N′-diethylethylenediamine,N,N′-dimethyl-1,3-propanediamine, N,N′-diethyl-1,3-propanediamine,N,N′-dimethyl-1,4-butanediamine, N,N′-diethyl-1,4-butanediamine, andN,N′-dimethyl-1,6-hexanediamine; and diamines in which R⁴ and R⁵ inFormula (a-2) are identical or different and linear or branched alkylgroups, R⁶ and R⁷ are hydrogen atoms, and R⁸ is a linear or branchedalkylene group, such as N,N-dimethylethylenediamine,N,N-diethylethylenediamine, N,N-dimethyl-1,3-propanediamine,N,N-diethyl-1,3-propanediamine, N,N-dimethyl-1,4-butanediamine,N,N-diethyl-1,4-butanediamine, and N,N-dimethyl-1,6-hexanediamine.

Among them, diamines in which R⁴ and R⁵ in Formula (a-2) above areidentical or different and linear or branched alkyl groups, R⁶ and R⁷are hydrogen atoms, and R⁸ is a linear or branched alkylene group [inparticular, diamines in which R⁴ and R⁵ in Formula (a-2) are linearalkyl groups, R⁶ and R⁷ are hydrogen atoms, and R⁸ is a linear alkylenegroup] are preferred.

In diamines in which R⁴ and R⁵ in Formula (a-2) are identical ordifferent and are linear or branched alkyl groups, and R⁶ and R⁷ arehydrogen atoms, that is, diamines having a primary amino group and atertiary amino group, the primary amino group has a high coordinationability to a metal atom, but the tertiary amino group has a poorcoordination ability to a metal atom, and thus this prevents a resultingcomplex from becoming excessively complicated, thereby allowing thecomplex to be thermally decomposed at lower temperature and in a shortertime in the thermal decomposition of the complex. Among them, diamineshaving 6 or less (e.g., from 1 to 6, preferably from 4 to 6) carbonatoms in total are preferred, and diamines having 5 or less (e.g., from1 to 5, preferably from 4 to 5) carbon atoms in total are more preferredin that they can be removed from the metal nanoparticle surfaces in ashort time in low-temperature sintering.

The proportion of the content of the monoamine (1) in the total amountof the organic protective agent contained in the electrically conductiveink according to an embodiment of the present invention, and theproportion of the total content of the monoamine (2) and the diamine (3)therein are preferably within the ranges described below.

Content of monoamine (1): for example, from 5 to 65 mol % (the lowerlimit is preferably 10 mol %, particularly preferably 20 mol %, and mostpreferably 30 mol %. In addition, the upper limit is preferably 60 mol%, and particularly preferably 50 mol %)

Total content of monoamine (2) and diamine (3): for example, from 35 to95 mol % (the lower limit is preferably 40 mol %, and particularlypreferably 50 mol %. In addition, the upper limit is preferably 90 mol%, particularly preferably 80 mol %, and most preferably 70 mol %)

The proportion of the content of the monoamine (2) in the total amountof the organic protective agent contained in the electrically conductiveink according to an embodiment of the present invention, and theproportion of the content of the diamine (3) therein are preferablywithin the ranges described below.

Content of monoamine (2): for example, from 5 to 65 mol % (the lowerlimit is preferably 10 mol %, particularly preferably 20 mol %, and mostpreferably 30 mol %. In addition, the upper limit is preferably 60 mol%, and particularly preferably 50 mol %)

Content of diamine (3): for example, from 5 to 50 mol % (the lower limitis preferably 10 mol %. In addition, the upper limit is preferably 40mol %, and particularly preferably 30 mol %)

The monoamine (1) contained in the above range provides dispersionstability of the metal nanoparticles. With the content of the monoamine(1) below the above range, the metal nanoparticles would tend to beprone to agglomeration. On the other hand, the content of the monoamine(1) exceeding the above range would cause difficulty in removing theorganic protective agent from the metal nanoparticle surfaces in a shorttime when the sintering temperature is low, tending to reduce theelectrical conductivity of the resulting sintered body.

The monoamine (2) contained in the above range provides the effect ofpromoting complex formation. In addition, this allows the organicprotective agent to be removed from the metal nanoparticle surfaces in ashort time even when the sintering temperature is low, providing asintered body with excellent electrical conductivity.

The diamine (3) contained in the above range easily provides the effectof promoting complex formation and the effect of promoting the thermaldecomposition of the complex. In addition, the surface-modified metalnanoparticles having a configuration of being coated with the protectiveagent containing the diamine (3) exhibit excellent dispersion stabilityin a highly polar dispersion medium.

In an embodiment of the present invention, the use of the monoamine (2)and/or the diamine (3) having a high coordination ability to metal atomsof the metal compound is preferred, in that the use can reduce theamount of the monoamine (1) used depending on the proportion of themonoamine (2) and/or the diamine (3) used and can remove the organicprotective agent from the metal nanoparticle surfaces in a short timeeven when the sintering temperature is low, providing a sintered bodywith excellent electrical conductivity.

The amine used as the organic protective agent in an embodiment of thepresent invention may contain an additional amine other than themonoamine (1), the monoamine (2), and the diamine (3), but theproportion of the total content of the monoamine (1) and the monoamine(2), and the diamine (3) accounting for the total amines contained inthe protective agent is, for example, preferably from 60 wt. % orgreater, particularly preferably 80 wt. % or greater, and mostpreferably 90 wt. % or greater. Note that the upper limit is 100 wt. %.That is, the content of the additional amine is preferably not greaterthan 40 wt. %, particularly preferably not greater than 20 wt. %, andmost preferably not greater than 10 wt. %.

The amount of the organic protective agent [in particular, monoamine(1)+monoamine (2)+diamine (3)] used is not particularly limited but ispreferably approximately from 1 to 50 mol, particularly preferably from2 to 50 mol, and most preferably from 6 to 50 mol, relative to 1 mol ofmetal atoms in the metal compound of the raw material. When the amountof the organic protective agent is below the above range, the metalcompound not converted to a complex would be prone to remain in theformation of the complex, tending to be difficult to impart sufficientdispersibility to the metal nanoparticles.

To further improve the dispersibility of the metal nanoparticles, one ormore types of compounds having a carboxyl group (for example, compoundshaving from 4 to 18 carbon atoms and having a carboxyl group, preferablyaliphatic monocarboxylic acids having from 4 to 18 carbon atoms) may becontained together with the compound having an amino group as theorganic protective agent.

Examples of the aliphatic monocarboxylic acid may include saturatedaliphatic monocarboxylic acids having 4 or more carbon atoms, such asbutanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoicacid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid,tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoicacid, heptadecanoic acid, octadecanoic acid, nonadecanoic acid, andicosanoic acid; and unsaturated aliphatic monocarboxylic acids having 8or more carbon atoms, such as oleic acid, elaidic acid, linoleic acid,palmitoleic acid, and eicosenoic acid.

Among them, saturated or unsaturated aliphatic monocarboxylic acidshaving from 8 to 18 carbon atoms (in particular, octanoic acid and oleicacid) are preferred. When the carboxyl groups of the aliphaticmonocarboxylic acid are adsorbed on the metal nanoparticle surfaces, thesaturated or unsaturated aliphatic hydrocarbon chain having from 8 to 18carbon atoms causes a steric hindrance and thus can provide spacebetween the metal nanoparticles, thus improving the effect of preventingagglomeration of the metal nanoparticles.

The amount of the compound having a carboxyl group used is, for example,approximately from 0.05 to 10 mol, preferably from 0.1 to 5 mol, andparticularly preferably from 0.5 to 2 mol, relative to 1 mol of metalatoms in the metal compound. The amount of the compound having acarboxyl group used below the above range would cause difficulty inproviding an effect of improving dispersion stability. On the otherhand, the compound having a carboxyl group, even when used in anexcessive amount, would saturate the effect of improving the dispersionstability while it tends to be difficult to remove the compound bylow-temperature sintering.

The reaction between the organic protective agent and the metal compoundis performed in the presence or absence of the dispersion medium. As thedispersion medium, for example, an alcohol having 3 or more carbon atomscan be used.

Examples of the alcohol having 3 or more carbon atoms include n-propanol(boiling point: 97° C.), isopropanol (boiling point: 82° C.), n-butanol(boiling point: 117° C.), isobutanol (boiling point: 107.89° C.),sec-butanol (boiling point: 99.5° C.), tert-butanol (boiling point:82.45° C.), n-pentanol (boiling point: 136° C.), n-hexanol (boilingpoint: 156° C.), n-octanol (boiling point: 194° C.), and 2-octanol(boiling point: 174° C.). Among them, alcohols having from 4 to 6 carbonatoms are preferred, and in particular, n-butanol and n-hexanol arepreferred in that higher temperature can be set for the thermaldecomposition of the complex to be performed later and in terms of theconvenience of the post-treatment of the resulting surface-modifiedmetal nanoparticles.

In addition, the amount of the dispersion medium used is, for example,not less than 120 parts by weight, preferably not less than 130 parts byweight, and more preferably not less than 150 parts by weight, relativeto 100 parts by weight of the metal compound. The upper limit of theamount of the dispersion medium used is, for example, 1000 parts byweight, preferably 800 parts by weight, and particularly preferably 500parts by weight.

The reaction between the organic protective agent and the metal compoundis preferably performed at ordinary temperature (from 5 to 40° C.). Thereaction is accompanied by heat generation due to the coordinationreaction of the organic protective agent to the metal compound and thusmay be performed while the reaction mixture is appropriately cooled tothe above temperature range.

The reaction time between the organic protective agent and the metalcompound is, for example, approximately from 30 minutes to 3 hours. Thisresults in a metal-organic protective agent complex (metal-amine complexwhen an amine is used as the organic protective agent).

Thermal Decomposition

The thermal decomposition is a step of thermally decomposing theresulting metal-organic protective agent complex through the formationof the complex to form the surface-modified metal nanoparticles. It isbelieved that the metal-organic protective agent complex is heated tocause thermal decomposition of the metal compound to form metal atomswhile maintaining coordination bonding of the organic protective agentto the metal atoms, and then agglomeration of the metal atoms to whichthe organic protective agent is coordinated, leading to formation ofmetal nanoparticles that are coated with an organic protective film.

The thermal decomposition is preferably performed in the presence of adispersion medium, and the alcohol described above can be suitably usedas the dispersion medium. In addition, the thermal decompositiontemperature is to be a temperature at which the surface-modified metalnanoparticles are formed, and when the metal-organic protective agentcomplex is a silver oxalate-organic protective agent complex, thetemperature is, for example, approximately from 80 to 120° C.,preferably from 95 to 115° C., and particularly preferably from 100 to110° C. In terms of preventing the elimination of the surfacemodification portion of the surface-modified metal nanoparticle, thethermal decomposition is preferably performed at a temperature as low aspossible within the above temperature range. The thermal decompositionduration is, for example, approximately from 10 minutes to 5 hours.

In addition, the thermal decomposition of the metal-organic protectiveagent complex is preferably performed in an air atmosphere or in aninert gas atmosphere, such as argon.

(Washing Step)

The excess organic protective agent, if present after the completion ofthe thermal decomposition reaction of the metal-organic protective agentcomplex, is preferably removed by decantation, which may be repeatedonce or more times as necessary. In addition, the surface-modified metalnanoparticles after the completion of the decantation is preferablysubjected to the preparation of the electrically conductive inkdescribed below in a wet state without drying or solidifying in thatthis can prevent re-agglomeration of the surface-modified metalnanoparticles and maintain high dispersibility.

Decantation is performed, for example, by washing the surface-modifiedmetal nanoparticles in a suspended state with a cleaning agent,precipitating the surface-modified metal nanoparticles bycentrifugation, and removing the supernatant. The cleaning agent used ispreferably one or more types of linear or branched alcohols having from1 to 4 (preferably from 1 to 2) carbon atoms, such as methanol, ethanol,n-propanol, or isopropanol in terms of achieving good precipitation ofthe surface-modified metal nanoparticles and efficiently separating andremoving the cleaning agent by centrifugation after the washing.

In an embodiment of the present invention, the ink used in the inkjetprinting (hereinafter, also referred to as “ink for inkjet printing”)can be prepared by mixing the surface-modified metal nanoparticlesobtained through the above steps (preferably, surface-modified metalnanoparticles in a wet state), a dispersion medium, and, if necessary,an additive. For the mixing, a commonly known mixing apparatus, such as,for example, a self-rotating stirring defoaming apparatus, ahomogenizer, a planetary mixer, a three-roll mill, or a bead mill, canbe used. In addition, each component may be mixed at the same time orsequentially. The mixing portion of each component can be appropriatelyadjusted in the range described below.

The content of the surface-modified metal nanoparticles (in terms ofmetal elements) in the total amount of the ink for inkjet printing (100wt. %) is, for example, approximately from 35 to 70 wt. %. The lowerlimit is preferably 40 wt. %, particularly preferably 45 wt. %, mostpreferably 50 wt. %, and particularly preferably 55 wt. % from theperspective of obtaining a coating film or sintered body with a higherfilm thickness. The upper limit is preferably 65 wt. %, and particularlypreferably 60 wt. % from the perspective of coatability (stability ofejection from the head nozzle when applied by inkjet printing).

As the dispersion medium contained in the ink for inkjet printingdescribed above, a common organic solvent can be used without particularlimitation, and examples thereof include aliphatic hydrocarbon solventssuch as pentane, hexane, heptane, octane, nonane, decane, undecane,dodecane, tridecane, and tetradecane; aromatic hydrocarbon solvents suchas toluene, xylene, and mesitylene; and alcohol solvents such asmethanol, ethanol, propanol, n-butanol, n-pentanol, n-hexanol,n-heptanol, n-octanol, n-nonanol, n-decanol, and terpineol. Depending onthe desired concentration and viscosity, the type and amount of organicsolvent can be appropriately selected. One type of organic solvent usedin the dispersion medium can be used alone, or two or more of thereofcan be used in combination.

The content of the dispersion medium (in terms of metal elements) in theink for inkjet printing is from 20 to 100 parts by weight, preferablyfrom 30 to 90 parts by weight, more preferably from 40 to 80 parts byweight, even more preferably from 50 to 75 parts by weight, particularlypreferably from 55 to 75 parts by weight, and most preferably from 60 to75 parts by weight per 100 parts by weight of the surface-modified metalnanoparticles.

The content of the dispersion medium in the total amount of the ink forinkjet printing (100 wt. %) is, for example, from 20 to 65 wt. %,preferably from 25 to 60 wt. %, more preferably from 30 to 55 wt. %, andmost preferably from 30 to 50 wt. %. The ink for inkjet printingcontains the dispersion medium in an amount within the range describedabove and thus has excellent coatability. So, the ink for inkjetprinting, when applied by inkjet printing, can well maintain stabilityof ejection from the nozzle of the head.

The viscosity (at 25° C. and shear rate 10 (1/s)) of the ink for inkjetprinting is from 1 to 100 mPa·s, for example. The upper limit of theviscosity is preferably 50 mPa·s, particularly preferably 20 mPa·s, andmost preferably 15 mPa·s. The lower limit of the viscosity is preferably2 mPa·s, particularly preferably 3 mPa·s, and most preferably 5 mPa·s.

The obtained ink for inkjet printing described above can be used also ina printing process other than inkjet printing, for example, gravureprinting, flexographic printing, and the like.

The screen printing in an embodiment of the present invention is amethod that includes transferring a wiring pattern to the optical memberby squeezing the ink containing the electrically conductive substance(extruding the ink with a squeegee) to allow the ink to pass through ascreen having an opening corresponding to the wiring pattern.

The ink containing the electrically conductive substance used in thescreen printing according to an embodiment of the present invention(hereinafter, also referred to as “ink for screen printing”) is notparticularly limited as long as it can be used for screen printing. Fromthe perspective of easily forming a wire of a desired width at a targetposition of the optical member, an ink containing surface-modified metalnanoparticles is preferred, and a silver ink is particularly preferred.

The “surface-modified metal nanoparticles” contained in the ink forscreen printing described above can be the same as the “surface-modifiedmetal nanoparticles” used in the ink for inkjet printing describedabove, and can be available from a similar method.

The ink for screen printing described above can be prepared by mixingthe surface-modified metal nanoparticles described above (preferably,surface-modified metal nanoparticles in a wet state), a solvent, and, ifnecessary, an additive. For the mixing, a commonly known mixingapparatus, such as, for example, a self-rotating stirring defoamingapparatus, a homogenizer, a planetary mixer, a three-roll mill, or abead mill, can be used. In addition, each component may be mixed at thesame time or sequentially. The mixing portion of each component can beappropriately adjusted in the range described below.

The content of the surface-modified metal nanoparticles in the totalamount of the ink for screen printing (100 wt. %) is, for example, from60 to 85 wt. %, and the lower limit is preferably 70 wt. % in that theeffect of improving steady contact to the optical member is obtained.The upper limit of the content is preferably 80 wt. % and particularlypreferably 75 wt. %.

As the solvent contained in the ink for screen printing described above,a common organic solvent can be used without particular limitation, andexamples thereof include aliphatic hydrocarbon solvents such as pentane,hexane, heptane, octane, nonane, decane, undecane, dodecane, tridecane,and tetradecane; aromatic hydrocarbon solvents such as toluene, xylene,and mesitylene; and alcohol solvents such as methanol, ethanol,propanol, n-butanol, n-pentanol, n-hexanol, n-heptanol, n-octanol,n-nonanol, n-decanol, and terpineol. Since clogging of a screen platecaused by volatilization of the solvent is suppressed, and continuousprinting is thus possible, at least a terpene solvent is preferablycontained in the ink for screen printing.

The terpene solvent preferably has a boiling point of 130° C. of higher(for example, from 130 to 300° C., and preferably from 200 to 300° C.).

Furthermore, a viscosity (at 20° C.) of the terpene solvent is, forexample, from 50 to 250 mPa·s (particularly preferably from 100 to 250mPa·s, most preferably from 150 to 250 mPa.$), and the use of theviscosity is preferred in that the viscosity of the obtained ink forscreen printing can be appropriately increased, and thin lines can bedrawn with excellent precision. Note that the viscosity of the solventis a value at 20° C. and a shear rate of 20 (1/s) measured using arheometer (trade name “Physica MCR301”, available from Anton Paar).

Examples of the terpene solvent include4-(1′-acetoxy-1′-methylester)-cyclohexanol acetate,1,2,5,6-tetrahydrobenzyl alcohol, 1,2,5,6-tetrahydrobenzyl acetate,cyclohexyl acetate, 2-methylcyclohexyl acetate; 4-t-butylcyclohexylacetate, terpineol, dihydroterpineol, dihydroterpinyl acetate,α-terpineol, β-terpineol, γ-terpineol, L-α-terpineol,dihydroterpinyloxyethanol, tarpinyl methyl ether, and dihydroterpinylmethyl ether. One of these solvents can be used alone or two or more incombination. In the present invention, for example, the trade names“Terusolve MTPH”, “Terusolve IPG”, “Terusolve IPG-Ac”, “TerusolveIPG-2Ac”, “Terpineol C” (mixtures of α-terpineol, β-terpineol, andγ-terpineol, boiling point: 218° C.; viscosity: 54 mPa·s), “TerusolveDTO-210”, “Terusolve THA-90”, “Terusolve THA-70” (boiling point: 223°C., viscosity: 198 mPa·s), “Terusolve TOE-100” (all available fromNippon Terpene Chemicals, Inc.), and the like can be used.

The solvent used in the ink for screen printing described above maycontain one or more types of other solvents in addition to the terpenesolvent. Examples of other solvents include glycol ether solvents havinga boiling point of 130° C. or higher.

Examples of the glycol ether solvent may include compounds representedby Formula (b) below:R¹¹—(O—R¹³)_(m)—OR¹²   (b)

wherein R¹¹ and R¹² are identical or different and represent alkyl oracyl groups, R¹³ represents an alkylene group having from 1 to 6 carbonatoms, and m represents an integer of 1 or greater.

Examples of the alkyl groups in R¹¹ and R¹² described above may includelinear or branched alkyl groups having from 1 to 10 carbon atoms(preferably, from 1 to 5).

Examples of the acyl groups (RCO-groups) in R¹¹ and R¹² described abovemay include acyl groups (for example, acetyl groups, propionyl groups,butyryl groups, isobutyryl groups, and pivaloyl groups) in which Rdescribed above is a linear or branched alkyl group having from 1 to 10carbon atoms (preferably, from 1 to 5).

Among these, a compound in which R¹¹ and R¹² in Formula (b) are groupsdifferent from each other (different alkyl groups, different acylgroups, or an alkyl group and an acyl group) is preferred, and acompound in which R¹¹ and R¹² in Formula (b) are alkyl groups differentfrom each other is particularly preferred. A compound including a linearor branched alkyl group having from 4 to 10 carbon atoms (preferablyfrom 4 to 6) and a linear or branched alkyl group having from 1 to 3carbon atoms is most preferred.

Examples of such an alkylene group in R¹³ described above include amethylene group, a methylmethylene group, a dimethylmethylene group, anethylene group, a propylene group, a trimethylene group, atetramethylene group, a pentamethylene group, and a hexamethylene group.In an embodiment of the present invention, among these, an alkylenegroup having from 1 to 4 carbon atoms is preferred, and an alkylenegroup having from 1 to 3 carbon atoms is particularly preferred. Analkylene group having from 2 to 3 carbon atoms is most preferred.

m is an integer of 1 or greater and, for example, an integer of from 1to 8, preferably an integer of from 1 to 3, and particularly preferablyan integer of from 2 to 3.

The boiling point of the compound represented by Formula (b) is, forexample, 130° C. or higher (for example, from 130 to 300° C.),preferably 170° C. or higher, and particularly preferably 200° C. orhigher.

Examples of the compound represented by Formula (b) include glycoldiether, glycol ether acetate, and glycol diacetate such as ethyleneglycol methyl ether acetate (boiling point: 145° C.), ethyleneglycol-n-butyl ether acetate (boiling point: 188° C.), propylene glycolmethyl-n-propyl ether (boiling point: 131° C.); propylene glycolmethyl-n-butyl ether (boiling point: 155° C.), propylene glycol methylisoamyl ether (boiling point: 176° C.), propylene glycol diacetate(boiling point: 190° C.), propylene glycol methyl ether acetate (boilingpoint: 146° C.), 3-methoxybutyl acetate (boiling point: 171° C.),1,3-butylene glycol diacetate (boiling point: 232° C.), 1,4-butanedioldiacetate (boiling point: 232° C.), 1,6-hexanediol diacetate (boilingpoint: 260° C.), diethylene glycol dimethyl ether (boiling point: 162°C.), diethylene glycol diethyl ether (boiling point: 189° C.),diethylene glycol dibutyl ether (boiling point: 256° C.), diethyleneglycol ethyl methyl ether (boiling point: 176° C.), diethylene glycolisopropyl methyl ether (boiling point: 179° C.), diethylene glycolmethyl-n-butyl ether (boiling point: 212° C.), diethylene glycol-n-butylether acetate (boiling point: 247° C.), diethylene glycol ethyl etheracetate (boiling point: 218° C.), diethylene glycol butyl ether acetate(boiling point: 246.8° C.), dipropylene glycol methyl-isopentyl ether(boiling point: 227° C.), dipropylene glycol dimethyl ether (boilingpoint: 175° C.), dipropylene glycol methyl-n-propyl ether (boilingpoint: 203° C.), dipropylene glycol methyl-n-butyl ether (boiling point:216° C.), dipropylene glycol methyl cyclopentyl ether (boiling point:286° C.), dipropylene glycol methyl ether acetate (boiling point: 195°C.), triethylene glycol dimethyl ether (boiling point: 216° C.),triethylene glycol methyl-n-butyl ether (boiling point: 261° C.),tripropylene glycol methyl-n-propyl ether (boiling point: 258° C.),tripropylene glycol dimethyl ether (boiling point: 215° C.), andtetraethylene glycol dimethyl ether (boiling point: 275° C.). One ofthese solvents can be used alone or two or more in combination.

Examples of the glycol ether solvent may include compounds (glycolmonoethers) represented by Formula (b′) below:R¹⁴—(O—R¹⁵)_(n)—OH   (b′)

wherein R¹⁴ represents an alkyl group or an aryl group, R¹⁵ representsan alkylene group having from 1 to 6 carbon atoms, and n represents aninteger of 1 or greater.

Examples of the alkyl group in R¹⁴ described above may include linear orbranched alkyl groups having from 1 to 10 carbon atoms (preferably, from1 to 5). Examples of the aryl group may include aryl groups having from6 to 10 carbon atoms (for example, phenyl groups).

Examples of the alkylene group in R¹⁵ described above include linear orbranched alkylene groups such as a methylene group, a methylmethylenegroup, a dimethylmethylene group, an ethylene group, a propylene group,a trimethylene group, a tetramethylene group, a pentamethylene group,and a hexamethylene group. Among these, an alkylene group having from 1to 4 carbon atoms is preferred, and an alkylene group having from 1 to 3carbon atoms is particularly preferred. An alkylene group having from 2to 3 carbon atoms is most preferred.

n is an integer of 1 or greater and, for example, an integer of from 1to 8, preferably an integer of from 1 to 3, and particularly preferablyan integer of from 2 to 3.

The boiling point of the compound represented by Formula (b′) is, forexample, 130° C. or higher (for example, from 130 to 310° C.),preferably from 130 to 250° C., particularly preferably from 130 to 200°C., most preferably from 130 to 180° C., and especially preferably from140 to 180° C.

Examples of the compound represented by Formula (b′) include ethyleneglycol monomethyl ether (boiling point: 124° C.), ethylene glycolmonoisopropyl ether (boiling point: 141.8° C.), ethylene glycolmonobutyl ether (boiling point: 171.2° C.), ethylene glycol monoisobutylether (boiling point: 160.5° C.), ethylene glycol monotert-butyl ether(boiling point: 152° C.), ethylene glycol monohexyl ether (boilingpoint: 208° C.), ethylene glycol mono-2-ethyl hexyl ether (boilingpoint: 229° C.), ethylene glycol monophenyl ether (boiling point: 244.7°C.), ethylene glycol monobenzyl ether (boiling point: 256° C.),diethylene glycol monomethyl ether (boiling point: 194° C.), diethyleneglycol monobutyl ether (=butyl carbitol, boiling point: 230° C.),diethylene glycol monoisobutyl ether (boiling point: 220° C.),diethylene glycol monoisopropyl ether (boiling point: 207° C.),diethylene glycol monopentyl ether (boiling point: 162° C.), diethyleneglycol monoisopentyl ether, diethylene glycol monohexyl ether (=hexylcarbitol, boiling point: 259.1° C.), diethylene glycol mono-2-ethylhexyl ether (boiling point: 272° C.), diethylene glycol monophenyl ether(boiling point: 283° C.), diethylene glycol monobenzyl ether (boilingpoint: 302° C.), triethylene glycol monomethyl ether (boiling point:249° C.), triethylene glycol monobutyl ether (boiling point: 271.2° C.),propylene glycol monoethyl ether (boiling point: 132.8° C.), propyleneglycol monopropyl ether (boiling point: 149° C.), propylene glycolmonobutyl ether (boiling point: 170° C.), dipropylene glycol monomethylether (boiling point: 188° C.), and 3-methoxy-1-butanol (boiling point:158° C.). One of these solvents can be used alone or two or more incombination.

The content of the terpene solvent in the total amount of the ink forscreen printing (100 wt. %) is, for example, from 5 to 30 wt. %, and thelower limit is preferably 10 wt. %, and particularly preferably 14 wt.%. The upper limit of the content is preferably 25 wt. % andparticularly preferably 18 wt. %. The terpene solvent contained in therange described above can provide the effect of suppressing bleeding andimproving the drawing accuracy of thin lines and the effect of improvingthe continuous printing properties.

The content of the compound represented by Formula (b) in the totalamount of the ink for screen printing (100 wt. %) is, for example, from0.5 to 5 wt. %, and the lower limit is preferably 1.6 wt. %. The upperlimit of the content is preferably 3 wt. % and particularly preferably 2wt. %. The blending of the compound represented by Formula (b) in anamount within the above range can impart thixotropy, make the edge of adrawing par sharper, and improve the printing accuracy. In addition, theeffect of improving continuous printing properties can also be obtained.

Additionally, the ink for screen printing can contain the compoundrepresented by Formula (b′) in an amount of 10 wt. % or less (from 5 to10 wt. %), and preferably 8.5 wt. % or less of the total amount of theink.

The ink for screen printing described above may contain, as a solventhaving a boiling point of 130° C. or higher, one or more types of ethyllactate acetate (boiling point: 181° C.), tetrahydrofurfuryl acetate(boiling point: 195° C.), tetrahydrofurfuryl alcohol (boiling point:176° C.), ethylene glycol (boiling point: 197° C.), and the like, inaddition to the compound represented by Formula (b) above and thecompound represented by Formula (b′) above. However, the content of suchother solvents having a boiling point of 130° C. or higher is 30 wt. %or less, preferably 20 wt. % or less, particularly preferably 15 wt. %or less, most preferably 10 wt. % or less, even more preferably 5 wt. %or less, and especially preferably 1 wt. % or less of the total amountof the solvent contained in the ink for screen printing.

Furthermore, the ink for screen printing may also contain a solventhaving a boiling point of lower than 130° C. [for example, ethyleneglycol dimethyl ether (boiling point: 85° C.), propylene glycolmonomethyl ether (boiling point: 120° C.), and propylene glycolmonomethyl ether (boiling point: 97° C.)]. The content of the solventhaving a boiling point of lower than 130° C. (total amount, if two ormore types are contained) in the total amount of the ink for screenprinting (100 wt. %) is preferably 20 wt. % or less, more preferably 10wt. % or less, particularly preferably 5 wt. % or less, and mostpreferably 1 wt. % or less. In the above ink for screen printing, whenthe content of the solvent having a boiling point of lower than 130° C.is suppressed to the range described above, clogging of the screen platecaused by volatilization of the solvent can be suppressed, andcontinuous printing is thus easily possible.

One type of solvent used in the above ink for screen printing can beused alone, or two or more of thereof can be used in combination.

The ink for screen printing described above can contain, in addition tothe above components, an additive such as a binder resin, a surfaceenergy modifier, a plasticizer, a leveling agent, an antifoaming agent,or a tackifier, as necessary. Among these, a binder resin is preferablycontained in that the effect of improving the steady contact andflexibility of a sintered body to the optical member can be obtained,the sintered body being obtained by applying (or printing) the ink forscreen printing onto the optical member and then sintering.

Examples of the binder resin include vinyl chloride-vinyl acetatecopolymer resins, polyvinyl butyral resins, polyester resins, acrylicresins, and cellulosic resins. One of these solvents can be used aloneor two or more in combination. Of these, a cellulosic resin ispreferably used, and commercially available products such as the tradenames “ETHOCEL std.200” and “ETHOCEL std.300” (both available from TheDow Chemical Company) can be used.

The content of the binder resin (for example, cellulosic resin) is, forexample, approximately from 0.5 to 5.0 wt. %, and preferably from 1.0 to3.0 wt. % of the total amount of the ink for screen printing.

The viscosity (at 25° C., shear rate 10 (1/s)) of the ink for screenprinting is, for example, 60 Pa·s or greater, preferably 70 Pa·s orgreater, more preferably 80 Pa·s or greater, even more preferably 90 Pas or greater, even more preferably 100 Pa s or greater, and particularlypreferably 150 Pa·s or greater. The upper limit of the viscosity is, forexample, approximately 500 Pa·s, preferably 450 Pa·s, particularlypreferably 400 Pa·s, and most preferably 350 Pa·s.

The viscosity (at 25° C. and shear rate 100 (1/s)) of the above ink forscreen printing is, for example, from 10 to 100 Pa·s, and the upperlimit thereof is preferably 80 Pa·s, particularly preferably 60 Pa·s,most preferably 50 mPa·s, and especially preferably 40 Pa·s. The lowerlimit of the viscosity is preferably 15 Pa·s, particularly preferably 20Pa·s, most preferably 25 Pa·s, and especially preferably 30 Pa·s.

The ink for screen printing preferably has thixotropy, and the TI valueat 25° C. (viscosity at a shear rate of 10 (1/s)/viscosity at a shearrate of 100 (1/s)) is in a range of for example from 3.0 to 10.0,preferably from 3.5 to 7.0, particularly preferably from 4.0 to 6.5,most preferably from 4.5 to 6.3, and especially preferably from 4.8 to6.2.

As the ink for screen printing, a commercially available product, forexample, a silver paste ink (product name: NP-2910D1) available fromNoritake Co., Ltd. can also be used.

The method for forming the wire on the optical member according to anembodiment of the present invention includes applying the ink to theoptical member by a printing process, and sintering.

In the optical member according to an embodiment of the presentinvention, a known or commonly used surface treatment such as rougheningtreatment, adhesion-facilitating treatment, antistatic treatment, sandblast treatment (sand mat treatment), corona discharge treatment, plasmatreatment, excimer treatment, chemical etching treatment, water mattreatment, flame treatment, acid treatment, alkali treatment, oxidationtreatment, ultraviolet irradiation treatment, or silane coupling agenttreatment may be applied to the surface on which the wire is formed. Thenon-optical element region is preferred as the surface to besurface-treated. On the other hand, the optical element region may besurface-treated or not surface-treated.

The thickness of the coating film obtained by applying the ink ispreferably in a range such that the thickness of the sintered bodyobtained by sintering the coating film is, for example, from 0.1 to 5 μm(preferably, 0.5 to 2 μm).

The width of the coating film obtained by applying the above ink is notparticularly limited, and can be appropriately selected according to theshape, size, and the like of the optical member, and the width of thesintered body obtained by sintering the coating film is, for example,200 μm or less (for example, from 1 to 200 μm), and preferably in arange of from 10 to 100 μm.

By sintering the coating film formed above, the coating film can beformed into an electrically conductive wire (sintered body). Thesintering temperature is, for example, 150° C. or lower (the lower limitof the sintering temperature is, for example, 60° C., and is morepreferably 100° C. in that the coating film can be sintered in a shortperiod of time), particularly preferably 130° C. or lower, and mostpreferably 120° C. or lower. The sintering time is, for example, from0.5 to 3 hours, preferably from 0.5 to 2 hours, and particularlypreferably from 0.5 to 1 hour.

The width of the wire formed on the optical member according to anembodiment of the present invention is not particularly limited, and canbe appropriately selected according to the shape, size, and the like ofthe optical member, and is, for example, 200 μm or less (for example,from 1 to 200 μm), and preferably in a range of from 10 to 100 μm. Bysetting the width of the wire to be within this range, it becomes easierto ensure conduction.

In the optical member according to an embodiment of the presentinvention, the wire containing the electrically conductive substance isformed, and the position thereof is not particularly limited, but whenthe optical member includes the optical element region and thenon-optical element region described above, the wire is preferablyformed in the non-optical element region for the purpose of notimpairing the illumination of the laser light and the structural lightthat are emitted from the surface emitting laser light source andcontrolled by the optical element.

When the optical member according to an embodiment of the presentinvention has a substrate shape, the wire containing the electricallyconductive substance may be formed on only one side, or may be formed onboth sides.

When the ink containing the electrically conductive substance is appliedto the optical member by the printing process to form the wire, theoptical member is preferably an optical element array in which two ormore optical elements are arranged two-dimensionally. Specifically, itis preferable that two or more optical element regions be arrangedtwo-dimensionally, and preferably connected via a non-optical elementregion. By employing the optical element array, the wire containing theelectrically conductive substance can be formed collectively withrespect to each of the optical elements, and therefore productionefficiency is greatly improved.

The optical element array can be easily available from using a moldhaving a molding surface in which an inverted shape corresponding to twoor more optical elements arranged two-dimensionally on the opticalelement array is arranged two-dimensionally as the mold formanufacturing the optical member described above.

After the wire is applied to each of the optical elements arranged onthe optical element array, the optical member according to an embodimentof the present invention can be obtained by singulating each opticalelement. Specifically, by cutting the non-optical element regionconnecting the two or more optical element regions, the optical memberaccording to an embodiment of the present invention including thesingulated optical element regions can be obtained.

The process of singulating the optical element array into individualoptical elements is not particularly limited, and well-known andcommonly used means can be employed. Among others, a blade rotating athigh speed is preferably used.

In cutting using a blade rotating at high speed, the rotation speed ofthe blade is, for example, approximately from 10000 to 50000 rpm.Furthermore, cutting the array of optical elements using a bladerotating at high speed may generate frictional heat. Thus, it ispreferred to cut the array of optical elements while cooling, in termsof being able to suppress deformation of the optical elements andreduction in optical properties due to the frictional heat. Opticalelements obtained by cutting the optical element array at thenon-optical element region includes an optical element region and anon-optical element region on the periphery thereof.

FIG. 1, diagrams (a), (b), and (c) are schematic diagrams illustratingan example of a preferred embodiment of the optical member of thepresent invention. FIG. 1, diagram (a) is a perspective view, FIG. 1,diagram (b) is a top view, and FIG. 1, diagram (c) is a side view. Theoptical member 10 in FIG. 1 includes an optical element region 11 inwhich an optical element is formed in a lower surface central portion ofthe optical member 10, and also includes a non-optical element region 12in which no optical element is formed on the periphery of the opticalelement region 11 Note that no optical element is formed on the uppersurface of the optical member 10, but regions corresponding to theoptical element region 11 and the non-optical element region 12, whenviewed from the upper surface, are defined as the optical element region11 and the non-optical element region 12, respectively. The wire 13 isformed in the non-optical element region 12 on the upper surface of theoptical member 10 in such a manner that it surrounds the periphery ofthe optical element region 11. By arranging the wire 13 in this manner,in a case where damage such as cracking occurs in the optical elementregion 11 of the optical member 10, the wire 13 breaks and fails to beconductive. Therefore, by monitoring the conducting state of the wire13, damage such as cracking, in particular, spanning the optical elementregion 11, of the optical member 10 can be detected. On both ends of thewire 13, a conduction detection mechanism connection portion 14 thatconnects to a conduction detection mechanism described below is formed.

In FIG. 1, one side of the optical member 10 (square on the uppersurface) is approximately 2 mm, one side of the optical element region(square) is approximately 1 mm, the thickness is approximately 300 μm,the total light transmittance is approximately 90%, and the haze isapproximately 0.5%.

FIG. 2, diagrams (a) and (b) are schematic diagrams illustrating anotherexample of the preferred embodiment of the optical member of the presentinvention. FIG. 2, diagram (a) is a top view, and FIG. 2, diagram (b) isa cross-sectional view taken along X-X′. The optical member 20 in FIG. 2includes an optical element region 11 in which an optical element isformed in a lower surface central portion of the optical member 20, andalso includes a non-optical element region 12 in which no opticalelement is formed on the periphery of the optical element region 11 Thewire 13 is formed in the non-optical element region 12 on the lowersurface of the optical member 20 in such a manner that it surrounds theperiphery of the optical element region 11. In a case where cracking orthe like occurs in the optical element region 11 of the optical member20, the wire 13 breaks and fails to be conductive. Therefore, similarlyto FIG. 1, by monitoring the conducting state of the wire 13, damagesuch as cracking, in particular, spanning the optical element region 11,of the optical member 10 can be detected. On both ends of the wire 13, aconduction detection mechanism connection portion 14 that connects to aconduction detection mechanism described below is formed. Additionally,the conduction detection mechanism connection portion 14 is formed on atip end of a protrusion 15 protruding from the lower surface of theoptical member 20. By forming the conduction detection mechanismconnection portion 14 on the tip end of the protrusion 15, it is easilyconnected to the conduction detection mechanism, as illustrated in FIG.4 described below.

[Surface Emitting Laser Light Source]

A laser module including the optical member according to an embodimentof the present invention includes a surface emitting laser light sourceas a light source. The surface emitting laser light source used in anembodiment of the present invention is not particularly limited,includes a Vertical Cavity Surface Emitting Laser (VCSEL) and a VerticalExternal Cavity Surface Emitting Laser (VECSEL) with a cavity externalthereto, and is preferably VCSEL because it is commonly used in 3Dsensing and low in cost.

The laser light emitted by the surface emitting laser light source maybe visible light or ultraviolet light or infrared rays, but nearinfrared radiation having a wavelength of from 750 to 2500 nm, which ishighly safe and often used in 3D sensing, is preferred. In particular,near infrared radiation having a wavelength of from 800 to 1000 nm whichis not susceptible to environmental light such as sunlight isparticularly preferred. The output light intensity is not particularlylimited and can be selected appropriately according to the applicationand purpose.

[Laser Module]

The laser module according to an embodiment of the present inventionincludes the optical member according to an embodiment of the presentinvention and the surface emitting laser light source described above.Embodiments of the laser module according to an embodiment of thepresent invention are not particularly limited as long as it is arrangedin such a manner that the laser light emitted from the surface emittinglaser light source passes through the optical member (preferably,optical element region formed in the optical member). When the opticalmember includes an optical element, the laser light passing through theoptical element region is controlled and shaped into uniform light,structural light, or the like.

FIG. 3, diagrams (a) and (b) are schematic views illustrating an exampleof a preferred embodiment of the laser module of the present invention.FIG. 3, diagram (a) is a perspective view, and FIG. 3, diagram (b) is across-sectional view taken along Y-Y′ and Z-Z′. In a laser module 30 ofFIG. 3, a surface emitting laser light source 33 such as VCSEL isarranged on a center upper portion of a substrate 31, and an opticalmember 10 is further arranged above the substrate 31 via a spacer 32. Anoptical element region 11 is arranged in the center portion of the lowersurface of the optical member 10, and is in contact with the spacer 32at an outer edge portion of a non-optical element region 12 in the lowersurface. A wire 13 is formed in the non-optical element region 12 on anouter periphery of the upper surface of the optical member 10, andconduction detection mechanism connection portions 14 are formed on bothends of the wire 13, which connect to a conduction detection mechanismdescribed below. Laser light 34 emitted by the surface emitting laserlight source 33 passes through an optical element such as a microlensarray or an optical diffraction grating in the optical element region 11and is emitted from the laser module 30 as laser light 35 controlled andshaped into uniform or structural light.

In the event of cracking or other damage spanning the optical elementregion 11 of the optical member 10, the optical element in the opticalelement region 11 is unable to function normally. The laser light 34 isnot sufficiently diffused in the optical element region 11, and isradiated from the laser module 30. Thus, defects or erroneous actuationmay be caused in the laser device mounted with the laser module 30. In acase where damage such as cracking occurs in the optical element region11 of the optical member 10, the wire 13 formed surrounding the opticalelement region 11 breaks and fails to be conductive. Accordingly, damageto the optical member 10 can be detected by monitoring the conductingstate of the wire 13.

In addition to the optical member and the surface emitting laser, thelaser module according to an embodiment of the present inventionpreferably further includes a conduction detection mechanism thatdetects a conducting state of the wire containing the electricallyconductive substance, which is included in the optical member. The formof the conduction detection mechanism is not particularly limited aslong as the conduction detection mechanism is capable of detecting theconducting state of the wire, but the form is preferably an aspecthaving an electrode connected to both ends of the wire.

FIG. 4 is a schematic cross-sectional view illustrating another exampleof the preferred embodiment of the laser module of the presentinvention. The laser module 40 in FIG. 4 has a configuration in whichthe optical member 20 in FIG. 2 is mounted on a conduction detectionmechanism 41, and, further, a substrate 31 and a surface emitting laserlight source 33 are arranged in the lower portion of the optical member20. The conduction detection mechanism 41 includes a retainer 43 forholding the optical member 20 and an electrode 42 laminated on theretainer 43. The electrode 42 is not particularly limited as long as itis conductive, but is preferably made of copper. The retainer 43 has aprotrusion 43 a on an upper periphery thereof, and the optical member 20is housed inside the retainer 43. The electrode 42 is stacked on theinner surface and the upper surface of the retainer 43, and the upperend of the electrode 42 is in contact with the conduction detectionmechanism connection portion 14 of the optical member 20 and retains theoptical member 20 from below. The lower end of the electrode 42 isconnected with a conduction detector (not illustrated) with the otherelectrode to monitor the conducting state of the wire 13. When damagesuch as cracking occurs in the optical member 20, damage to the opticalmember 20 can be detected by detecting that the wire 13 breaks and failsto be conductive.

The laser module according to an embodiment of the present invention canbe suitably used as a laser module for generating depth information in3D sensing. Examples of the method for generating depth informationinclude a Time of Flight (TOF) method, a structured light method, astereo matching method, and a Structure from Motion (SfM) method. TheTOF method is a method of irradiating a target space with near infraredradiation, receiving reflected light in an object in the target space,measuring a time from irradiation with the near infrared radiation untilreceiving the reflected light, and determining a distance to the objectin the target space based on the time. Furthermore, the structured lightmethod is a method of projecting a predetermined projection pattern ofnear infrared radiation on an object present in a target space, anddetecting a shape (depth) of the object present in the target space onthe basis of the state of deformation of the projection pattern.Furthermore, the stereo matching method is a method of determining adistance to a subject based on a parallax between two captured images ofthe subject captured from different positions. Furthermore, the SfMmethod is a method of performing depth detection by calculating arelationship between images, such as registration of feature points,using a plurality of captured images captured from different angles, andperforming optimization.

[Laser Device]

The laser device according to an embodiment of the present inventionincludes the laser module according to an embodiment of the presentinvention.

The laser device according to an embodiment of the present inventionincludes the laser module according to an embodiment of the presentinvention, and thus can easily detect damage such as cracking, peeling,and the like of the optical member used in the laser module. Therefore,defects of the laser module caused by damage to the optical member andinjuries caused by erroneous actuation can be prevented. Accordingly,the laser device according to an embodiment of the present invention canbe suitably used in 3D sensing applications suited to suchcharacteristics. For example, in face authentication of a smartphone,attention can be attracted by sending an error message to the user, orthe laser light itself is not emitted, thereby preventing the user'seyes from being directly irradiated with the laser light and reducing arisk of blindness and the like. Also, in automatic driving of anautomobile, defects in a 3D sensing system mounted with the laser moduleare detected, and error messages or the like are sent to the driver,thereby making it possible to prevent accidents caused by erroneousactuation. It can also be suitably used in any application using 3Dsensing, such as a recognition camera for 3D mapping, a gesturerecognition controller for a gaming device, automatic driving of anautomobile, and machine vision in a plant.

EXAMPLES

Hereinafter, the present invention will be described in more detailbased on examples, but the present invention is not limited by theseexamples.

Manufacture Example 1 (Manufacture of Optical Member not Provided withWire)

An epoxy resin (CELVENUS106; available from Daicel Co., Ltd.) (5 g) wasadded dropwise onto a disk-shaped silicone resin substrate in which 9×9inversion patterns of diffractive optical elements were arranged in onesection (2.5 mm in length×2.5 mm in width) with a diameter of 100 mm.The mold was closed, with the thickness of a flat silicone resinsubstrate having the same size being approximately 0.3 mm. UVirradiation was performed at 100 mW/cm²×30 seconds. When the upper andlower silicone resin substrates were removed, an optical member in which9×9 diffractive optical elements were arranged in one disk-shapedsection (2.5 mm in length×2.5 mm in width) was obtained as a curedproduct of the epoxy resin.

Manufacture Example 2 (Manufacture of Optical Member not Provided withWire)

An epoxy resin (CELVENUS106; available from Daicel Co., Ltd.) (5 g) wasadded dropwise onto a disk-shaped silicone resin substrate in which 9×9inversion patterns of diffractive optical elements were arranged in onesection (2.5 mm in length×2.5 mm in width) with a diameter of 100 mm.The mold was closed, with the thickness of a flat glass substrate havingthe same size being approximately 0.3 mm. UV irradiation was performedat 100 mW/cm²×30 seconds. When the silicone resin substrate on the lowermold was removed, an optical member was obtained in which a curedproduct layer of the epoxy resin in which 9×9 diffractive opticalelements were arranged in one section (2.5 mm in length×horizontal 2.5mm) was laminated on the glass substrate.

Manufacture Example 3 (Preparation of Surface-Modified SilverNanoparticles)

Formation of Complex

Silver oxalate (molecular weight: 303.78) was obtained from silvernitrate (available from Wako Pure Chemical Industries, Ltd.) and oxalicacid dihydrate (available from Wako Pure Chemical Industries, Ltd.).

Then, 20.0 g (65.8 mmol) of the silver oxalate was charged to a 500-mLflask, 30.0 g of n-butanol was added to this, and an n-butanol slurry ofsilver oxalate was prepared.

To this slurry, an amine mixture liquid of 57.8 g (790.1 mmol) ofn-butylamine (a molecular weight of 73.14, available from DaicelCorporation), 40.0 g (395.0 mmol) of n-hexylamine (a molecular weight of101.19, available from Tokyo Chemical Industry Co., Ltd.), 38.3 g (296.3mmol) of n-octylamine (a molecular weight of 129.25, trade designation“FARMIN 08D”, available from Kao Corporation), 18.3 g (98.8 mmol) ofn-dodecylamine (a molecular weight of 185.35, trade designation “FARMIN20D”, available from Kao Corporation), and 40.4 g (395.0 mmol) ofN,N-dimethyl-1,3-propanediamine (a molecular weight of 102.18, availablefrom Koei Chemical Co., Ltd.) was added dropwise at 30° C.

After the dropwise addition, the mixture was stirred at 30° C. for 2hours to allow a complex forming reaction between silver oxalate and theamines to proceeded, and a white material (silver oxalate-amine complex)was obtained.

Thermal Decomposition

After the formation of the silver oxalate-amine complex, the reactionsolution temperature was raised from 30° C. to approximately 105° C.(from 103 to 108° C.), then the silver oxalate-amine complex wasthermally decomposed by heating for 1 hour in a state of maintaining thetemperature, and a dark blue suspension in which surface-modified silvernanoparticles were suspended in the amine mixture liquid was obtained.

Washing

After cooling, 200 g of methanol was added to the resulting suspension,and the mixture was stirred. Then, the surface-modified silvernanoparticles were precipitated by centrifugation, and the supernatantwas removed. Then, 60 g of methanol was added again, and the mixture wasstirred, then the surface-modified silver nanoparticles wereprecipitated by centrifugation, and the supernatant was removed.Surface-modified silver nanoparticles in a wet state were thus obtained.

Manufacture Example 4 (Preparation of Silver Ink for Inkjet Printing)

The dispersion medium was mixed with the surface-modified silvernanoparticles obtained in Manufacture Example 3 to obtain a black brownsilver ink for inkjet printing.

Example 1 (Inkjet Printing)

The silver ink for inkjet printing obtained in Manufacture Example 4 wasfilled into an inkjet printer, and a wire was printed on one side of thedisk-shaped optical member obtained in Manufacture Example 1 in such amanner that it surrounded the periphery of each of the diffractiveoptical elements in which 9×9 sections (2.5 mm in length×2.5 mm in widthfor each section) were arranged. The optical member on which the wirewas printed was sintered using a hot plate, and an optical member wasobtained in which a wire having a thickness of approximately 1 μm and awidth of approximately 50 μm was arranged in an array.

The optical member having the wire obtained in an array was singulatedinto an optical member having each of the wires using a dicing apparatus(DAD3350, available from DICSO) mounted with a dicing blade (availablefrom DISCO) having a thickness of 0.1 μm.

Example 2 (Inkjet Printing)

The silver ink for inkjet printing obtained in Manufacture Example 4 wasfilled into an inkjet printer, and a wire was printed on the glasssubstrate surface of the disk-shaped optical member obtained inManufacture Example 2 in such a manner that it surrounded the peripheryof each of the diffractive optical elements in which 9×9 sections (2.5mm in length×2.5 mm in width for each section) were arranged. Theoptical member on which the wire was printed was sintered using a hotplate, and an optical member was obtained in which a wire having athickness of approximately 1 μm and a width of approximately 50 μm wasarranged in an array.

The optical member having the wire obtained in an array was singulatedinto an optical member having each of the wires using a dicing apparatus(DAD3350, available from DICSO) mounted with a dicing blade (availablefrom DISCO) having a thickness of 0.1 μm.

Example 3 (Screen Printing)

With silver paste ink (product name: NP-2910D1), available from NoritakeCo., Ltd., a wire was printed on the glass surface of the disk-shapedoptical member obtained in Manufacture Example 2 at 25° C. using ascreen printing apparatus (LS-150TV, available from NEWLONG SEIMITSUKOGYO Co., Ltd.) in such a manner that it surrounded the periphery ofeach of the diffractive optical elements in which 9×9 sections (2.5 mmin length×2.5 mm in width for each section) were arranged. The opticalmember on which the wire was printed was sintered using a hot plate, andan optical member was obtained in which a wire having a thickness ofapproximately 1 μm and a width of approximately 50 μm was arranged in anarray.

The optical member having the wire obtained in an array was singulatedinto an optical member having each of the wires using a dicing apparatus(DAD3350, available from DICSO) mounted with a dicing blade (availablefrom DISCO) having a thickness of 0.1 μm.

Example 4 (Screen Printing)

With silver paste ink (product name: NP-2910D1), available from NoritakeCo., Ltd., a wire was printed on one side of the disk-shaped opticalmember obtained in Manufacture Example 1 at 25° C. using a screenprinting apparatus (LS-150TV, available from NEWLONG SEIMITSU KOGYO Co.,Ltd.) in such a manner that it surrounded the periphery of each of thediffractive optical elements in which 9×9 sections (2.5 mm in length×2.5mm in width for each section) were arranged. The optical member on whichthe wire was printed was sintered using a hot plate, and an opticalmember was obtained in which a wire having a thickness of approximately1 μm and a width of approximately 50 μm was arranged in an array.

The optical member having the wire obtained in an array was singulatedinto an optical member having each of the wires using a dicing apparatus(DAD3350, available from DICSO) mounted with a dicing blade (availablefrom DISCO) having a thickness of 0.1 μm.

Evaluation Test (Reflow Heat Resistance Test)

The conduction of the wire was confirmed by connecting the tester toboth ends of the wire of the singulated optical member obtained inExample 1. The resistance value was 4.4 Ω Thereafter, the optical memberwas placed in a simple reflow furnace (available from Shinapex Co.,Ltd.), and a heat resistance test based on the reflow temperatureprofile (maximum temperature: 260° C.) prescribed in JEDEC standard wasapplied three times sequentially, and then the conduction of the wire ofthe optical member after heat treatment by the reflow furnace waschecked. The resistance value was 2.0 Ω As a result, it was confirmedthat no damage such as cracks occurred in the optical member of Example1 even after heat treatment using the reflow furnace.

Variations of embodiments of the present invention described above areadditionally described below.

[1] An optical member for use in a laser module including a surfaceemitting laser light source, the optical member including a wirecontaining an electrically conductive substance.

[2] The optical member according to [1], wherein the optical member isformed from at least one type selected from the group consisting ofplastic and inorganic glass.

[3] The optical member according to [1] or [2], wherein the opticalmember is plastic or a laminate of plastic and inorganic glass.

[4] The optical member according to [3], wherein the laminate is alaminate in which a plastic layer on which an optical element is formedis laminated on one side of a substrate made of flat inorganic glass.

[5] The optical member according to [3] or [4], wherein the plastic is acured product of a curable epoxy resin composition.

[6] The optical member according to [5], wherein the curable epoxy resincomposition contains a polyfunctional alicyclic epoxy compound.

[7] The optical member according to [6], wherein the polyfunctionalalicyclic epoxy compound includes at least one type of compound selectedfrom the group consisting of (i) to (iii) below:

a compound (i) including an epoxy group (an alicyclic epoxy group)constituted of two adjacent carbon atoms and an oxygen atom thatconstitute an alicyclic ring;

a compound (ii) including an epoxy group directly bonded to an alicyclicring with a single bond; and

a compound (iii) including an alicyclic ring and a glycidyl group.

[8] The optical member according to [7], wherein the compound (i) havingan alicyclic epoxy group includes a compound represented by Formula (i)below:

wherein X represents a single bond or a linking group (a divalent grouphaving one or more atoms; and a substituent (for example, such as analkyl group) may be bonded to a cyclohexene oxide group.

[9] The optical member according to [8], wherein the compound (i)includes (3,4,3′,4′-diepoxy)bicyclohexyl.

[10] The optical member according to any one of [1] to [9], wherein theoptical member includes an optical element (for example, a diffractiveoptical element, a microlens array, a prism, a polarizing plate, or thelike).

[11] The optical member of any one of [1] to [10], wherein the opticalmember includes at least one type of optical element selected from thegroup consisting of a diffractive optical element and a microlens array.

[12] The optical member according to [10] or [11], wherein the opticalmember has a substrate shape and includes a region in which an opticalelement is formed (hereinafter, also referred to as “optical elementregion”) and a region in which no optical element is formed(hereinafter, also referred to as “non-optical element region”).

[13] The optical member according to [12], wherein the optical elementregion is formed in a center portion of the substrate of the opticalmember, and the non-optical element region is provided on the peripheryof the optical element region (outer periphery of the substrate of theoptical member).

[14] The optical member according to [12] or [13], wherein the wire isformed in the non-optical element region of the optical member.

[15] The optical member according to [13] or [14], wherein the wire isformed in the non-optical element region of the optical member in such amanner that it surrounds the periphery of the optical element region.

[16] The optical member according to any one of [1] to [15], wherein thewire has a width of not greater than 200 μm (for example, from 1 to 200μm, and preferably from 10 to 100 μm).

[17] The optical member according to any one of [1] to [16], wherein theelectrically conductive substance includes at least one type selectedfrom the group consisting of a metal, a metal oxide, an electricallyconductive polymer, and an electrically conductive carbon-basedsubstance.

[18] The optical member according to any one of [1] to [17], wherein theelectrically conductive substance includes a metal (e.g., gold, silver,copper, chromium, nickel, palladium, aluminum, iron, platinum,molybdenum, tungsten, zinc, lead, cobalt, titanium, zirconium, indium,rhodium, ruthenium, and alloys thereof).

[19] The optical member according to any one of [1] to [18], wherein theelectrically conductive substance includes silver.

[20] A method for manufacturing the optical member described in any oneof [1] to [19], the method including:

applying an ink containing an electrically conductive substance to anoptical member by a printing process to form the wire.

[21] The method for manufacturing the optical member according to [20],wherein the printing process includes inkjet printing or screenprinting.

[22] The method for manufacturing the optical member according to [20]or

[21], wherein the ink containing the electrically conductive substanceis an ink containing surface-modified metal nanoparticles having aconfiguration in which surfaces of the metal nanoparticles are coatedwith an organic protective agent (hereinafter, also referred to as“surface-modified metal nanoparticles”).

[23] The method for manufacturing the optical member according to [22],wherein the surface-modified metal nanoparticles each consist of a metalnanoparticle portion and a surface modification portion that covers themetal nanoparticle portion, and the proportion of the surfacemodification portion is from 1 to 20 wt. % (preferably, from 1 to 10 wt.%) of the weight of the metal nanoparticle portion.

[24] The method for manufacturing the optical member according to [23],wherein the metal nanoparticle portion has an average primary particlediameter of from 0.5 to 100 nm (preferably from 0.5 to 80 nm, morepreferably from 1 to 70 nm, and even more preferably from 1 to 60 nm).

[25] The method for manufacturing the optical member according to [23]or [24], wherein the metal that constitutes the metal nanoparticleportion is at least one type (preferably silver) selected from the groupconsisting of gold, silver, copper, nickel, aluminum, rhodium, cobalt,and ruthenium.

[26] The method for manufacturing the optical member according to anyone of [22] to [25], wherein the organic protective agent thatconstitutes the surface modification portion of the surface-modifiedmetal nanoparticle includes a compound having from 4 to 18 carbon atomsand having an amino group (an amine having from 4 to 18 carbon atoms).

[27] The method for manufacturing the optical member according to anyone of [22] to [26], wherein the organic protective agent thatconstitutes the surface modification portion of the surface-modifiedmetal nanoparticle contains, as amines, a monoamine (1) having 6 or morecarbon atoms in total, and a monoamine (2) having 5 or less carbon atomsin total and/or a diamine (3) having 8 or less carbon atoms in total.

[28] The method for manufacturing the optical member according to anyone of [20] to [27], wherein the optical member is an optical elementarray in which two or more optical elements are arrangedtwo-dimensionally.

[29] The method for manufacturing the optical member according to [28],further including singulating the optical element array into the two ormore optical elements by dicing.

[30] A laser module including the optical member described in any one of[1] to [19] and a surface emitting laser light source.

[31] The laser module according to [30], wherein laser light emitted bythe surface emitting laser light source includes near infrared radiationhaving a wavelength of from 800 to 1000 nm.

[32] The laser module according to [30] or [31], further including aconduction detection mechanism for detecting a conducting state of thewire containing the electrically conductive substance, which is includedin the optical member.

[33] The laser module according to [32], wherein the conductiondetection mechanism includes an electrode connected to both ends of thewire.

[34] The laser module according to any one of [30] to [33], which is alaser module for generating depth information in 3D sensing.

[35] The laser module according to [34], wherein a method for generatingdepth information includes at least one type selected from the groupconsisting of a Time of Flight (TOF) method, a structured light method,a stereo matching method, and a Structure from Motion (SfM) method.

[36] A laser device including the laser module described in any one of[30] to [35].

[37] The laser device according to [36], which is used in 3D sensingselected from the group consisting of face authentication of asmartphone, automatic driving of an automobile, recognition cameras for3D mapping, gesture recognition controllers for gaming devices, andmachine vision in a plant.

INDUSTRIAL APPLICABILITY

The optical member, laser module including the optical member, and laserdevice of the present invention can be suitably used in 3D sensing suchas face authentication of a smartphone, automatic driving of anautomobile, recognition cameras for 3D mapping, gesture recognitioncontrollers for gaming devices, and machine vision in a plant.

REFERENCE SIGNS LIST

-   10, 20: Optical member-   11: Optical element region-   12: Non-optical element region-   13: Wire containing electrically conductive substance-   14: Conduction detection mechanism connection portion-   30, 40: Laser module-   31: Substrate-   32: Spacer-   33: Surface emitting laser light source-   34: Laser light emitted from surface emitting laser light source-   35: Laser light emitted from laser module-   41: Conduction detection mechanism-   42: Electrode-   43: Retainer for optical member

The invention claimed is:
 1. An optical member for use in a lasermodule, the laser module including a surface emitting laser lightsource, wherein the optical member comprises a wire containing anelectrically conductive substance, the optical member includes inorganicglass is a laminate of plastic and inorganic glass, and the opticalmember is disposed so that laser light emitted by the surface emittinglaser light source passes through an optical element region of theoptical member.
 2. The optical member according to claim 1, wherein theelectrically conductive substance comprises a metal.
 3. The opticalmember according to claim 1, wherein the electrically conductivesubstance comprises silver.
 4. The optical member according to claim 1,wherein the optical member comprises at least one type of opticalelement selected from the group consisting of a diffractive opticalelement and a microlens array.
 5. The optical member according to claim1, wherein the plastic is a cured product of a curable epoxy resincomposition.
 6. A laser module comprising the optical member describedin claim 1 and the surface emitting laser light source.
 7. The lasermodule according to claim 6, further comprising a conduction detectionmechanism configured to detect a conducting state of the wire containingthe electrically conductive substance, which is included in the opticalmember.
 8. A laser device comprising the laser module described in claim6.
 9. A method for manufacturing the optical member described in claim1, the method comprising: applying an ink containing an electricallyconductive substance to an optical member by a printing process to formthe wire.
 10. The method for manufacturing the optical member accordingto claim 9, wherein the printing process includes inkjet printing orscreen printing.
 11. The method for manufacturing the optical memberaccording to claim 9, wherein the optical member is an optical elementarray in which two or more optical elements are arrangedtwo-dimensionally.
 12. The method for manufacturing the optical memberaccording to claim 11, further comprising singulating the opticalelement array into the two or more optical elements by dicing.
 13. Theoptical member according to claim 1, wherein the optical membercomprises a diffractive optical element (DOE).
 14. The optical memberaccording to claim 1, wherein the wire is on the inorganic glass of thelaminate.
 15. The optical member according to claim 1, wherein the wireis printed on the inorganic glass of the laminate.
 16. The opticalmember according to claim 1, wherein the optical member comprises amicrolens array.
 17. The optical member according to claim 1, whereinthe wire is disposed on a surface of the optical member in an open-endedarrangement.
 18. An optical member for use in a laser module, the lasermodule including a surface emitting laser light source, wherein theoptical member comprises a wire containing an electrically conductivesubstance and an optical element, the optical member has a substrateshape, and the wire and the optical element region are on oppositesurfaces of the optical member.
 19. The optical member according toclaim 18, further comprising a connection detection mechanism portionarranged on a protrusion of the optical member.
 20. The optical memberaccording to claim 18, wherein the wire at least partially surrounds anoptical element region of the optical member, the optical element regionincluding the optical element.
 21. The optical member according to claim18, wherein ends of the wire are not connected on a same surface as theoptical element.